The rubber boot for my cat tore after a couple days. The rubber is thin and not tough.

Rubber sleeves protect the sensor from water, they don't last forever but does what it needs to do! :)

Simplified & quality to eliminate problems.

The boot is for my old unit because the plastic clip that the strap went through broke off. I need something for the strap to go through so I can use it as a backup if the new one ever fails.

My dogs play ruff. And my dogs have damaged a collar so it quit transmitting to open the door. So I purchased the rubber boot for it. It gives me a sense of security that the collar is protected from their ruff playing.