Which type of soft copper tubing do you use for a DIY wort chiller?

[msa8967]

Local big box store offers a variety of types of soft copper tubing (L, M and UT utility grade). Curious to know which type of soft copper tubing do you use for a DIY wort chiller? How about thickness 1/2 inch or 3/8 inch?

 

[kh54s10]

I used the cheapest one! 20ft coils @ $19 when I did it. I made 2 sections. In the winter both go into the pot. In the summer one goes in the BK and the other in a bucket of water and ice.

 

[jmpreiks]

This is the cheapest 25' coil I could find, worked great for me:
http://www.amazon.com/gp/product/B001AH8HDO/?tag=skimlinks_replacement-20