Marine grade nylon cap and base.Flush mount.O-ring seal.Cap retainer chain.Other Details: Part No. Type Hose Size Ø Flange O.D.(mm) Cut OutØ (mm) Protrusion(mm) Intrusion(mm) Mount Screw(mm) (mm) (in) 29825 Water 38 1-1/2" 90 55 16 65 5 c/s 29837 Water 50 2" 90 55 16 65 5 c/s