10 Important Question About Co2 Laser -co2 Laser 10 जरूरी सवाल

10 Important Question About Co2 Laser
नमस्कार दोस्तों
सफीदों क्राफ्ट में आपका स्वागत है।
दोस्तों मुझे डेली बहुत सरे कमेंट आ रहे थे। आप में से बहुत से लोगो ने मुझे कॉल भी किया। उसी सब से मैंने ये वीडियो बनाने की सोचा। ये वीडियो उनके भी काम आने वाली है जिन्हे नया मशीन लेना है और जो ले चुके है उनके भी।
इस वीडियो में मैंने लेज़र मशीन से सम्बंधित कुछ सवालो को लिया है। जिनके जवाब आपको पता होना जरुरी है।
तो दोस्तों बने रहे मेरे साथ इस वीडियो में हो सकता है आप जिस सवाल का जवाब खोजने के लिए वीडियो देख रहे हो उसका जवाब इसी वीडियो में आपको मिल जाए। वीडियो को लास्ट तक देखे और अगर आपको उसके बाद भी कुछ जानना है तो कमेंट बॉक्स में कमेंट छोड़ दे ,हम रिप्लाई जरूर करेंगे।
तो चलिए सुरु करे इस वीडियो को।
हर बार की तरह इस बार भी खुदका प्रमोशन खुदसे
तो दोस्तों अगर आपको लेज़र कटाई के designs की आवश्यकता है तो आप हमसे कांटेक्ट कर सकते है। साथ ही मशीन की ट्रेनिंग भी हमसे संपर्क कर सकते है।
Whatsap numner 930-691-6434(whtsapp Only)
Follow Us On Instagram
craftsafidon?ig...
Designs Cdr Catalog
for Lasercutting Designs Visit on . safidoncraft.com/
Co2 Laser Trainging Course
play.google.com/store/apps/de...
10 Important Question About Co2 Laser
Hello Friends!
Welcome to Safidon Craft.
Friends, I was getting many comments daily. Many of you also called me. That's why I thought of making this video. This video is going to be useful for those who want to buy a new machine and also for those who have already bought it.
In this video I have taken some questions related to laser machine. Whose answers you need to know.
So friends, stay with me in this video, maybe you will find the answer to the question you are watching the video to find the answer in this video. Watch the video till the end and if you want to know anything even after that, then leave a comment in the comment box, we will definitely reply.
So let's start this video.
Like every time, this time also self-promotion
So friends if you need laser cutting design then you can contact us. Also you can contact us for machine training.
co2 laser engraver
150 watt laser cutter
laser machine co2
laser engraving machine price
50wco2lasercuttingmachine
co2 tempered glass cutting machine
60 watt laser cutting machine
1325 laser cutting machine
1410 laser cutting machine
co2 metal laser cutting machine
mehta co2 laser machine
80w co2 laser engraver cutting machine
metal and non metal laser cutting machine
laser cutting machine glass
co2 laser machine manufacturer
co2 laser machine working
cdr file download,laser ,co2 laser ,Co2 laser cutting machine
laser designs
cnc cutting design for wall
ms cnc cutting design
steel cnc cutting design
laser cutting jali
cnc cutting jali design
jali cnc cutting design
cnc cutting jali price
acrylic cnc cutting design
#co2 #premmandir #vrindavan #laserdesign #lasersolutions #lasertraining #gifts #laserbusinessidea
#150wattlasercutter
#bestco2laser
#topco2laser
#laserbusiness
#workingwithlaser
#howtoworkwithco2laser

[@yashpalsharma8368]

Imandari se kaam ker rhe ho .ise hamesha banaye rakhiye ga.khoob tarakki milegi.❤🎉😊

[@SafidonCraft]

G sir g ,ye hi to ek chij h mere pass, thanks for your love ❤️

[@ganeshcracharla5042]

Acha explained ji

[@SafidonCraft]

Thanks 😊

[@legalhunt8445]

Very informative 👍👍

[@SafidonCraft]

Thanks 😊

[@sanjaykandekar9211]

Bahot badhiya and useful information specially for new buyers thank you very much.

[@SafidonCraft]

Thanks 😊

[@kishorraviraj]

Bhut achcha jankari 💞

[@SafidonCraft]

Please keep supporting

[@shivacofancyfish1148]

सही जानकारी का खजाना ------👍👍👌👌👌

[@SafidonCraft]

Aabhar

[@sslgift3452]

Hello Jitender Kumar Apka Video Muje Asa laga Very good information

[@SafidonCraft]

Thanks, please keep supporting

[@yogeshverma-pq8zf]

Kya bat h bhai ..itna khul k koi nahi samjhta ❤

[@SafidonCraft]

Thanks

[@shaikhghouse408]

zabardast bhai

[@SafidonCraft]

Thanks 🙏

[@dayalsingh6137]

Bahut badiya jankari di bhai sab mane arc sign ki m2 lesar machine liya he

[@SafidonCraft]

Thanks, please keep supporting 🙏

[@prakashmeena1252]

Thank you for wonderfull information.

[@SafidonCraft]

Thanks, please keep supporting

[@user-nd6rd7ts5u]

Very good information thaxs bro

[@SafidonCraft]

Thanks, please keep supporting

[@sanjaykandekar9211]

Thanks for detailed info.

[@SafidonCraft]

Please keep supporting

[@manoharhonganurahobalarao6462]

good information

[@SafidonCraft]

Thanks

[@AvGraphics.]

Very nice video bro thanks

[@SafidonCraft]

Thanks 🙏

[@legalhunt8445]

Bhai Jai Bheem

[@SafidonCraft]

Jai bhim

[@kishorraviraj]

Wah sir g

[@SafidonCraft]

thanks ,all about truth

[@ikeyradio6598]

Thanks bro 🙏

[@SafidonCraft]

Please keep supporting

[@kishorraviraj]

Mai sir se class kr rha hu...or mai bhut hi khush hu...Q ki mujhe bhut achhi jankari di sir ne...

[@SafidonCraft]

thanks,seekhna jaruri hai,ummed karta hu sahi jankari hi share karu

[@yamunap4686]

Sir se class kese le sakte hai bhai??

[@yamunap4686]

​@@SafidonCraftsir mujhe bhi jankari chahiye
Aapka class purchase karna hai

[@SafidonCraft]

Please lease massage on WhatsApp, number discription and video me h

[@amishpatel8812]

👌👍🙏

[@SafidonCraft]

Thanks

[@nadimimam6028]

❤

[@SafidonCraft]

Thanks for your love

[@mohitkhorwal1425]

Bhai thank you so much... mujhe loan ke paiso se leni thi ye and bach gya bhai teri badolat. thank you so much .... mujhe saari info mil gai jo me soch rha tha bas ek sawal hai ki quality kaise judge kare kyuki price se judge nahi kar sakte

[@SafidonCraft]

Macanism se hoti h,rest parts dekhne k bad bhi pata chal jata h, better information k liy WhatsApp pr contact kr sakte h

[@Priyanshushorts03.]

Kisi machine me hum kam watts ka tube ko update kar ke ke jyda watts kar skte g

[@SafidonCraft]

Depend hai ki machine me uske according supply laga hai ki nahi

[@ujjawalkumar2108]

Informative video sir
Love from SHIBOO GIFT ❤

[@SafidonCraft]

trying to maintain this love,Please keep loving

[@DeepakVerma-xs8wd]

Informative bhai
Bhai apne R&D course kya hai?

[@SafidonCraft]

may be its parts of joke,sab experience se milta hai

[@legalhunt8445]

Do we need to clean the lens everyday or after some particular quantity plz reply

[@SafidonCraft]

No need to clean everyday,just depend on use and dust on lences and mirror,but if you clean before starting,it increases machine performance

[@nitish10verma]

Sir tube ke liye jo paani use krte hai uska maximum temperature kitna ho sakta hai use krte samay.

[@SafidonCraft]

35 maximum

[@Ismail-nv2jj]

Main naye hu , lazer increasing ,machine Lena chahta hun, mujhe kon si kitne wat ki lena chahiye, please

[@SafidonCraft]

sir kai bate samjhni hoti h,whats pr massage kr dena reply mil jayega

[@gabodmaster]

Muje co2 laser machine se mdf keychains aur sublimation wale frames banane hai . Muje kaun sa co2 laser machine khardina chahiye ?

[@SafidonCraft]

Agar keychains me kam karna hai to double head 4x3 chahiye 130 watt

[@dabluproduction]

kya photoshop software use kar sakte hai

[@SafidonCraft]

G kam me jarurat padti h,but machine me nahi

[@sushilkumbha1547]

5 mm acrylic sheet katney ke liye kitney wt ki machine achhi rahygi

[@SafidonCraft]

Meri last video me iska answer hai

[@alkeshvora7382]

Great Video Bhai. Kya AKT ka machine lena chahiye chote kaam ke liye? Machine ki quality kaisi hai?.

[@SafidonCraft]

sir baki sabhi choti machino jaise hi machine h,choti machine se chote kam kiy ja sakte hai,sari bate samjh kar hi faisla le

[@alkeshvora7382]

@@SafidonCraft Thank you so much Bhai. Kya main aapko call kar sakta hoon. Phone number bataiyega. 🙏🏻

[@SafidonCraft]

Video me hai mera number,plz massage krna mai call kr lunga

[@alkeshvora7382]

@@SafidonCraft Ok Bhai. Thank you.

[@SafidonCraft]

Please keep supporting

[@GiftCraftin]

Sir ek head 100 w ek head 50w kra sakte hain wo haryana Fatehabad mein uti ki machine jada chal rhi hai aapne use ki hai ?

[@SafidonCraft]

Ji ,kisi friend k pass hai,china imported hi hi,pahle machine acha aata tha,,but uske bad bhi reaserch jaruri hai,koi to vjah hogi jo maine nahi li

[@SafidonCraft]

Sir tube hi hota h, normaly 80 watt ke sath setting krna hota h,ye machine ki company par depend hai ki set kar payenge ya nahi,dono ka power supply alg alg hota h,nozel lence size alg alg hota hai,aur bhi kai bato ka khyal rakhna hota h

[@vetcrypto]

Sir koi reliable refrence jha se hum machine kharid sake

[@SafidonCraft]

Kai bate samjhni hoti h uske bad aap dissison le pate ho,aap baat kr skte h, number video me h

[@santoshwaghmare1160]

Muze coral drw nai ata flexi 8 atahai chalega kya

[@SafidonCraft]

Kuch had tak chal jayega

[@SafidonCraft]

But Corel flexi se Jayda featured hai

[@user-iz2bf6eu9x]

Brother mai 3*2 feet ki co2 laser lena chahta hu 80watt ki to mujhe kitne ₹ ka budget rakhna chahiye.

[@SafidonCraft]

Kosish Kiya h sab samjhane ki sir ,is se Jayda WhatsApp PR dal sakte ho

[@huntymina7813]

Kya ese ghar mai laga sakte hai bhai or yadi ghar mai lagate hai to koi padosi objection kar sakta hai kya.or karta hai to koi problem to nahi hai please tell me sor

[@SafidonCraft]

Bilkul laga sakte hai,padosi Tak smoke na pahuche ye aapko dekhna h,single fase par machine chal sakta h

[@iplofficial468]

Sir CO2 machine kahase kharide best sellar konsa hai

[@SafidonCraft]

Best ko samjhne k liy,Kai bate samjhni padta h,aap mujhse baat kr skte ho

[@avnishtyagi9145]

I want to purchase for glass work, is it possible ?

[@SafidonCraft]

Engraving work can be possible,avoid if you want to cut glass

[@mukeshchandrarajora7631]

Suggest machine for name plate for military

[@SafidonCraft]

Sir many type se banti h,laser se bhi bnaya ja sakta h,aapki qty pr depend h

[@YashRastogiVlogs]

bhaiya imported vs indian me bhot confusion ho rahi ha please kuch btayein ?

[@SafidonCraft]

G bilkul, received your call

[@atichophi9548]

Bhaiya what's your feedback on dolphin company co2 lazer

[@SafidonCraft]

Nowadays I don't think it is a good idea

[@atichophi9548]

@@SafidonCraft why? Please share

[@atichophi9548]

@@SafidonCraft sir please update on what the best company or brand for co2 lazer machine 🙏

[@SafidonCraft]

Sir not possible in comments you can contact on WhatsApp

[@giftbreed]

Hum gift business chala rahe hai,
Chotti laser machine se start karna chahte hai,
Delhi me ek supplier se baat hui hai 60w ki
15x22" ka bed area hai
Kya sahi rahega ? Please reply

[@SafidonCraft]

Sir mere hissab se paisa waste hai, minimum 2x3

[@TheGamingM0use]

tube ki lifte kitni hoti h ?

[@SafidonCraft]

Ye working hours me hoti h, minimum 5000 hours , maximum depend on use,also depend on tube quality

[@jaibabamusicalgroup6354]

आपके पास आकर ट्रेनिंग ले सकते है क्या???
अगर हा तो कहा आए???
कृपया बताएं 🙏

[@SafidonCraft]

Sir mere pass aakar to nahi ho sakta ,but online bhi acha setup kiya h humne

[@onlineservices8487]

Only mobile 9h gilaas ke liye beta kitna wate ke chaye

[@SafidonCraft]

CO2 se mobile work se dur rahe ,mai apni pahli video me bahut bar bta Chuka hu

[@gurditsingh5972]

Cr or hr ki sheet cutting ho jayega

[@SafidonCraft]

Samjha nahi ,hmr sheet ?

[@sanjaychavan5795]

Chiller machine ke sath ata hai ki alag se lena padta hai

[@SafidonCraft]

Mujhe machine ke sath hi Mila h,kuch log machine ka price kam dikhane k liy chiller ko alg se charge karte hai

[@mdmasud4927]

aslamualikum vaiya.my name is Masud.i from Bangladesh. I have seen your video that's really knowledgeable.need your advise vayia.i want to cut mobile temper glass and back cover also i want to cut gift item and logo.please give me your valuable suggestion.

[@SafidonCraft]

Machines are not successful for mobile work in India , for Bangladesh can't say anything,while there is a big opportunity in the gift line,you have to choose the correct machine as well knowledge of the making process these items

[@mdmasud4927]

Thanks for your valuable suggestion.can i use plotter for Mobile work?please describe requirement about good gift line machine.again thank you.

[@SafidonCraft]

Yes plotter is best, you can leave massage on WhatsApp

[@mdmasud4927]

Hello vai.How are you? Please give me a suggestion what kind of plotter i should buy?i Don't want wase my time also my money.may be your suggestion can change a persons life.that’s it.

[@SafidonCraft]

Leave massage on WhatsApp

[@explore2live]

Sir second hand machine dilwa sakta hai kya agar kisi jaankar ke paas ho apki Nazar mai🙏🙏

[@SafidonCraft]

Bahut h sir

[@azharhusainhusain4298]

Hi bro co2laser machine flexi8. 1 me support karta hai plz reply

[@SafidonCraft]

Nahi ,laser ke supported software hote h

[@azharhusainhusain4298]

Thanks bro

[@SafidonCraft]

Please keep supporting 🙏

[@pareshgaliya2515]

Designs banak chahiye toh kitne Main ban sakta Hain?

[@SafidonCraft]

Depend on design

[@ssss-rv8lv]

Mv laser 6090 single head 120 w 375000 bol raha hain.. Price thik hain???

[@SafidonCraft]

Kv k price India me sabse Jayda h,aap WhatsApp karo basic guide kr dunga

[@world_class_interior]

Sir meri mashin size to jada cut kr rahi hy us ko kase thik kru

[@SafidonCraft]

Agar linier guide pr chal Rahi h to bely loose hoga

[@tontyart7585]

Wb IllamBazar se me mechine liyan ha ser nambar please

[@SafidonCraft]

Sir discription me h

[@anvicreation2049]

BHAIYA PRINT AND CUT KE BARE MEIN BATAIYA
I

[@SafidonCraft]

Ji koshish krte h koi video me btane ki

[@gurusirsi6846]

Sirjee I want CO2 120 what's software

[@SafidonCraft]

Aapka questions nhai samjha

[@TAJINDERARTIST]

Sir electricity bill kitna aa jaata hai is machine ka 1 month ka, generally jo b notice kiya ho apne beete kuch month me, plz btaaye

[@SafidonCraft]

Sir aap ye samjh lo k 1.5 ton ka ac lagva liya h aapne,

[@TAJINDERARTIST]

@@SafidonCraft bohot he kum hai bill to 130w ki machine k hisaab se👌👌

[@SafidonCraft]

Sir aap jitna Kam kar loge uske hissab se hi bill aayega,aur aap khusi khusi accept karoge,ki bill jayda nahi h

[@er.satish5]

Hd sticker ka design chahiye kya price h ?

[@SafidonCraft]

Sir design k lip aap www.safidoncraft.com visit kare

[@VikramArora-un8nk]

Sar ji kisi ke pass s machine acchi quality ki aur kam Chali Hui hoto batana kitne ki padegi

[@SafidonCraft]

WhatsApp par massage kar dena , number share kar denge

[@dharmendraupadhyay320]

सर एक 50 वाट की मशीन पर बाद में 100 वाट की ट्यूब लगा कर क्या मशीन की क्षमता बढ़ा सकते हैं? साथ में और कौन से पार्ट्स बदलने पड़ सकते हैं?

[@SafidonCraft]

Sir lagbhag sab kuch change hoga and uske bad bhi success nahi h,utne kharche me to new aa jayega

[@rjmagar4952]

bhai sahab co2 agar kharidte hai toh....uske sath sotware bhi aata hai ya nahi...aur jaise ki mobile skin plotter khardte hai toh har saal software ke liye paise kharcha karna padta hai isme woisa hi system hai ya nahi pls...clear kardijiyega bhai sahab

[@SafidonCraft]

Har ek machine ke command Dene ke liy ek software aata h,
Badi machine ke software ke sath koi design nahi aata,kyoki unko pata h ki kitna successful h

[@rjmagar4952]

@@SafidonCraft toh bhai sahab iska bhi software ke liye har saal paise pay karne padenge ya nahi ya life time tak koi charge nahi hai pls....kyu ki mai co2 mCHINE KHARIDNE KI PLAN KAR RAHA HOO...SIR MAI NEPAL SE HOOO

[@SafidonCraft]

Agar aapko Rd ka software milta h to lifetime free hota h,free updated software download kar sakte h

[@anujshivhare6628]

Sir co2 laser machine ka bijli bill kitna aata h kitni power consume krta h

[@SafidonCraft]

Normal 1.5 ton AC jitna hota h sir

[@creativedesigns7477]

Copper sheet par kaam karegi yeh

[@SafidonCraft]

Non metal machine hoti h

[@VikramArora-un8nk]

Sar ji kisi ke pass s machine acchi quality ki kam Chali Hui hoto bataen

[@SafidonCraft]

Last comment me WhatsApp krne k liy bola h Maine

[@mrkthasan4249]

I want to buy Laser cut MDF sheets 4.m.m thickness.....do you selling mdf sheets

[@SafidonCraft]

No sir but I can help you to buy

[@mrkthasan4249]

@@SafidonCraft Thankyou.... can you suggest genuine supplier for laser cut mdf sheets...i am having best services company 60 watts machine.... this machine can not cut local 4.m.m. thickness mdf sheets.can you please suggest supplier ...Thankyou

[@SafidonCraft]

Let's talk on WhatsApp

[@hirakjyotidutta6146]

Plz number ​@@SafidonCraft

[@Brandingwale759]

Ek machine maine dekha hai usme black jalne jaisi nishan aa jati hai cutting mein aur dusre machine me blkl bhi nhi aati aisa q hota hai kya reason hai plz reply

[@SafidonCraft]

Sir aap WhatsApp pe massage Kiya h, reply kiye hai maine

[@manoharhonganurahobalarao6462]

Are you giving training

[@SafidonCraft]

Yes

[@Shiva-xq6pv]

Aapke paas koi used machine hai kya agar hai to uski price kitni hai

[@SafidonCraft]

Allready replied

[@harishs8356]

How to cleaning honeycomb bed

[@SafidonCraft]

Need to wash with sprit

[@harishs8356]

​@@SafidonCraftif possible to one video... How to wash honeycomb bed

[@SafidonCraft]

Sorry lengthy,space consuming and ,too much time is required,will try to make it after Diwali

[@harishs8356]

Thank you sir

[@pankajmarvadi4703]

Bhai CO2 ke liye Design kaha se milega ?

[@pankajmarvadi4703]

Sir pls. Muje bhai design chahiye

[@SafidonCraft]

Ji aap mujhe what'app kar sakte hai, design paid hote h

[@alliswall4977]

Aap kha se ho

[@SafidonCraft]

Haryana

[@SAGARVERMARKE]

SELLING COST KESE NIKALE PRODUCT KI

[@SafidonCraft]

Cost plus 40%margon ,,than campare to market price,can be reduced for bulk order

[@chulgyan5581]

Hi sir kya mai aapse contact kr skte hu kya plz mujhe bhi ye karya krna hai laser work ka

[@SafidonCraft]

G bilkul,aap WhatsApp kar sakte h

[@chulgyan5581]

Bhai nmber kaha hai

[@SafidonCraft]

Discription me

[@shenphadsuradkar6211]

Sar muze kam sikna hai.aap sikasakte ho

[@SafidonCraft]

Ji mai training deta hu,aap bhi le sakte ho

[@prakharpachauri676]

Kaha bata sakte hae kya

[@SafidonCraft]

Sir online dete h

[@user-xd5qd8ww2d]

Apki location safidon me kaha hai

[@SafidonCraft]

G sir

[@user-xd5qd8ww2d]

@@SafidonCraft sir apne reply Kiya use liye thanks 😊 aap ki shop location kya hai mujhe janana tha main kurukshetra se hu
Aur iss project me interested hain

[@SafidonCraft]

Mai kurukshetra me kam kar raha hu, customer hai vaha mere HDFC Bank k pass h safidon me

[@user-xd5qd8ww2d]

@@SafidonCraft ok sir thank 😊

[@SafidonCraft]

Please keep supporting

[@mycoolbunny2.0]

Sir, main ek 50W ki CO2 Laser macgine lena chahata hu, Rubber Stamp Business ke liye, kyunki mere is kaam mein har ek minut bahot kimti hota hai, or ye par product dena bhi bahot jaruri hota hai. To agar main ek CO2 machine lu to wo kam se kam or zyada se zyada kitna MM tak engraving or cutting kar sakti hai. Kyunki mera primary work rubber stamp ka hi hai, to abhi photo-polymer pe kaam karna bhi bahot hi zyada time consuming lagta hai. Baki mera kaam nameplate bagera ka bhi hai.
So maine ek machine dekhi hai abhi ek 50W mein, jo ki 60K ki hai, M2 card wali, jismien alag alag kaam ke liye alag alag colora hote hai (engraving ke liye alag, cutting ke liye alag).
Use lena sahi hoga ya nahi. Yaa aap kisi acche se supplier ko jante hain to pls suggest kare.

[@SafidonCraft]

Sir 50 watt ka machine success full nahi hai,bahut problem aata hai,bahut se log jinhone liya hai vo sell krna chahte hai,paisa tak pura nahi kr paoge

[@mycoolbunny2.0]

@@SafidonCraft fir kitne watt ka lena sahi hoga, aap hi koi accha sa model suggest kar do. Kyunki main akele hi ek small business run karta hu, to apne kaam ko advanced karna chahata hu taki future ke liye benefits sabit ho sake. Abhi ji kam kart la hu akele usse kuch nahi hoga aane wale time mein, to aap hi koi best option suggest kar dijiye.
Kyunki paisa bar bar lagane ki chamta nahi hai meri.

[@SafidonCraft]

Minimum 80 watt ,2x3

[@Roysab..]

130 वॉट वाली मशीन की प्राइस क्या है सर?

[@SafidonCraft]

Please leave massage on WhatsApp,

[@AnilKumar-hl9ot]

Mujhe file chahiye thi

[@SafidonCraft]

Umeed hai aapko number mil gya hoga

[@SafidonCraft]

safidoncraft.com/

[@sutharahore8413]

4no ka alayment nahi bataye aap

[@SafidonCraft]

Alignment nozel ke center me hota h

[@Akshar_lamination]

Apko kitne me pada sar

[@SafidonCraft]

Leave massage on WhatsApp for price

[@anvicreation2049]

I MEAN ACRYLIC ID CARD OR ACRYLIC KEY CHAIN BANTE HAI JAISE

[@SafidonCraft]

sir special koi video banana padega ,dekhte h time ka Kami hota h

[@AnilKumar-hl9ot]

Aapka number kya h

[@SafidonCraft]

9306916434 WhatsApp only

[@growthyaancom]

4by 3 size ki machine kese rahegi sir

[@SafidonCraft]

Size 5o badiya h bus brand select krte time galti mat krna

[@Shiva-xq6pv]

Aapke paas koi used machine hai kya agar hai to uski price kitni hai

[@SafidonCraft]

Mai machine sell nhi krta,help kr skta hu