The rubber coating used for HA

I have a pair of Muse hearing aids which are fantastic for me.
The problem is because i’m an active sports person they are starting to move too much when sweating in my chosen sport.
When I first got them I had a thick rubber coating that used to give them grip even during me sweating.
Does anyone know what this coating is and perhaps you may know where I can get some?

Cheers
Colin

You might want a product like Ear Geer. It is a fabric slip-over that wicks sweat. It can be connected with a cord that will keep them from being lost should one detach.