Gasket Ring for Attix 30 - fits in a groove on the bottom of the motor head assembly and makes a tight seal to the canister. This gasket should be changed periodically to ensure a tight seal and optimum performance. If you own an Attix 50 and want to use the smaller/lighter Attix 30 canister, you'll need to purchase this gasket ring and remove the stock Attix 50 ring from the head assembly. See photo of the head assembly with the 2 separate grooves for the different sized gaskets.