Sea Dog Deck Fill, Gas. These Pipe Deck Fills are designed to be used in conjunction with 1-1/2" 0 11-1/2 NPSM straight threaded pipe. Cap diameter 2-1/8", thread pitch 11-1/2 NPSM straight. All fills and replacement caps (except waste) include attachment chain. Constructed of corrosion resistant investment cast 316 stainless steel. Installs with three #10 FH fasteners (not included). USCG regulations require bonding wire to prevent sparking.