The green & black single wall polyfin shrink tube is from Terminal Supply Company in Michigan and is sold in 4' lengths, IIRC. They have other colors as well. I experimented for a while using green instead of red shrink for power connections as a signature and to ID if someone messed with my wiring. I just kind of quit after a while and have standardized with black all around for savings and ease of inventory. I also now typically buy only dual wall adhesive and have been getting it from WayTek most recently, in pre-cut lengths, again for ease of inventory. For the above install, i just kind started wiring one night and used what was on hand. Would have preferred a bit more uniformity. Now, back to lurking...