These "O-Ring" bumpers will protect diffuser air stones from abrasives or protect a tank from abrasive diffusers. Holding the stone slightly off the tank bottom will also reduce back pressure by allowing air bubbles to be released from the bottom surface which is otherwise in contact with the tank bottom when stone is on its side. Use two (2) bumpers for each diffuser. The O-Ring is made of Buna 70 for an easy stretch over the 1-1/2" square diffusers.
NOTE: AIR STONE DIFFUSER IS NOT INCLUDED - SOLD SEPERATELY - BUY HERE