The PSS PRO Shaft Seal is a mechanical face seal utilizing our proven stainless steel and carbon sealing components, but adds a reinforced silicone bellow, we include external rings standard on sizes +2-1/4" and optional on all smaller sizes, a secondary shaft retention collar, 316 Stainless Steel hose clamps (rolled edges & non-perforated) and an optional Nitronic 50 rotor upgrade (for highly corrosive environments).