TIVO HD 'legs'

I'm looking for the 'legs' things that go under the TIVO. They are Gray color and made of some sort of rubber. All of them have broken on my TIVO HD's. On the first two I just put a piece of wood under it to lift the TIVO, so the air could circulate better. The wood is not stable and the TIVO shift if somebody bumps the furniture where the TIVO is. I have done some searches, but not been able to find anything. Don't even know exactly what is the correct term for that part is.