The PSS (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 PSS shaft seal 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. 1-1/2" shaft diameter. 2-1/2" - 2-5/8" stern-tube diameter. 9.175" length.