The P.S.S. (Packless Sealing System) shaft seal is a mechanical face seal that replaces the packing gland and is installed by builders and the USCG as standard equipment. The dripless operation of the P.S.S. eliminates needless bilge pumping, minimizes corrosion, and reduces maintenance by ending the need to adjust packing or replace shaft from damage due to the packing gland. Need to know both shaft and stern tube (shaft log) diameters to order.