This brass bullet will assist the installation of the piston stem o-ring of the first stage.

This tool is designed to fit most common models of simple piston first stages (unbalanced piston design with flow-by piston) on the market such as Scubapro MK2, Aqualung Calypso, Mares R2s, Sherwood Brut and Cressi AC2. For other pistons, see picture with maximum dimensions of the piston.

It is used by capping the bullet on the piston and simply slide down the stem o-ring into its groove.

Regulators or parts are not included.