I like coated kevlar. I use aluminum tube cut to about 3/8" length, crimped with electricians crimp to secure it. It doesn't stretch at all, and its non-metallic.. Don's Hobby in Salina, KS. is where I got it. He also sells whole kits for pull-pull with the coated kevlar. I've bought it in bulk though, and used it very successfully for flying wires on a few different aircraft. The coating is black, and with the coating it looks a tad thicker then a coated steel.. but its very tough stuff, and lightweight, wont' rust.. its almost not of this planet.