Review on Superior Resistance: Sterling Seal ORSIL210X10 Number 210 - Unmatched Durability by William Dean

I have no idea what these things are typically used for but I used them to eliminate pipe rattle on my Peavey Classic 30. The problem is that the speaker vibrates. Vacuum tubes versus small metal wires holding them in place. To fix this I put these silicone rings on each tube. I used one on top and one on the bottom for the larger EL84 bulbs and just one for the smaller 12AX7 bulbs. Because they are silicone, they won't be damaged by the heat of the pipes. This completely fixed the problem. Again, I have no idea what else they're used for, but for this purpose they're great!