Extender Silicone Tube Breaking

I’ve been using my rod extender (Pro extender) for over a year and I’m very pleased with the results! I basically use it daily and I had to find my own way to making it work. To keep it in place I use a small strap that keeps the silicone tube in place.

However lately I can’t last longer than a week with the silicone noose from tearing and breaking in half. The material just weakens after loosening and fastening constantly. Do you know if they sell these size silicone tubes in online hardware stores? Locally I can’t find them. Or is there an alternative noose that doesn’t break so easily? From a different material perhaps that you have used