Aluminum 2 1/2" NH Rocker Lug Plug Male Size_4 Inch National Pipe Tapered is common

National Pipe Tapered is common in plumbing and some industrial uses

The Pack completely unfolds for access and storage

If you have two swivel female FDC brass connections that need plugs measure the INSIDE diameter of the swivel fitting

Carbon Steel 4" Raised Faced ANSI 150 Flange x 5" Storz

Aluminum 2 1/2" NH Rocker Lug Plug Male Size_4 Inch National Pipe Tapered is commonAluminum plugs are fabricated from seamless extruded 6061 T6 aluminum and hard coat anodized per MIL A 8625 Type III, Class 1. Threads have a blunt start Higbee cut with indicators on adjacent lugs. Part identifications are permanent and stamped prior to hardcoat. Plugs and components meet the requirements of NFPA 1963. This is the most common plug size in the US. If your FDC or female swivel inside diameter is approx. 3 inches across, you probably