CAT TAILER Pet Tracker Silicone Sleeve Replacements - Two Pack Replacement Set, Lightweight, Durable

It's good that two are sold in the package, since the rubber itself rips if the wind blows. Trying to figure out how to keep the Cat Trailer on the collar without it.

Lasts long but if you have a pet that likes to chew on stuff, then having a back up should be a must