This is made by a company called Techflex. This stuff is pretty good. Check out the video above. I made a batch of slinky weights in late 2015. I left them out in the yard on the ground all winter and all spring. They have not rotted nor dry rotted from UV damage. They’re still supple and ready to fish.
When making slinky weights I use flame to melt the stuff. Man, I can’t get it to burn! It melts evenly. In fact it can get too hot to touch, but it doesn’t burn, lol. That’s great for making slinky weight all day in preparation for a fishing trip.