Reddit mentions of LASCO 17-0995 1/4-Inch Compression by 1/4-Inch Compression Brass Ball Valve

If he already has a 1/4" copper line add one of these valves on it than a short piece of copper than a 1/4" compression Union than a refrigerator flex all done

http://www.usplastic.com/mobile/item.aspx?sku=58305&gclid=coijvmtn_80cfqgoaqodjj4g6q


Or this compression valve on the copper than a refrigerator flex from the valve to the fridge

https://www.amazon.com/gp/aw/d/B008E33VA6/ref=pd_aw_sim_60_3?ie=UTF8&dpID=411vX%2Bz8GDL&dpSrc=sims&preST=_AC_UL100_SR100%2C100_&psc=1&refRID=0N8EMNKP16V290SCHRW2

edit, do you mean 3/8" nominal Cu pipe or 3/8" OD Cu tube?

You can likely use something like this for 3/8" OD Cu tube.

http://www.amazon.com/00084-060604-Compression-Tee-Reducing/dp/B00C04VY40/ref=sr_1_4?ie=UTF8&qid=1452542194&sr=8-4&keywords=3%2F8+1%2F4+reducing+tee+compression

then use a small piece of 1/4 tubing to connect the reducing tee to a valve

http://www.amazon.com/LASCO-17-0995-4-Inch-Compression-Brass/dp/B008E33VA6/ref=sr_1_1?ie=UTF8&qid=1452542253&sr=8-1&keywords=1%2F4+compression+valve

If for some reason you have lots of money and want nicer products you can pick these up from Swagelok or McMaster-Carr instead of generic stuff from Amazon.

I think a 3/8" Cu pipe has an OD of 1/2" So you can just get a 1/2" compression fitting and use that instead of the 3/8" fitting:

http://www.amazon.com/Aviditi-90809-2-Inch-Compression-Reducing/dp/B00AZEOUBG/ref=sr_1_2?ie=UTF8&qid=1452542716&sr=8-2&keywords=1%2F4+1%2F2+compression+reducing+tee

I would replace that with an inline brass compression valve (with the water off, obviously). Make sure that fridge side has plenty of tubing for pulling it in & out.