Plastic 2 1/2' NH Plug (Pin Lug): Industrial & Scientific. Plastic 2 1/2" NH Plug (Pin Lug): Industrial & Scientific. Weep Hole - No.Not intended for pressure applications.Pin lug plug constructed from hardened thermoplastic. Will fit 2 /2" NH/NST FDC female swivel outlets. Intended to keep debris out only, not for pressure applications..Temperature range from -4 F to 200 F. Removed from FDC with adjustable hydrant wrench. The most common plug and size in the US is 2 /2" NH / NST. This plug will fit into a female with an inside diameter of approx. 3 inches..This is the most common replacement plug size in the US. If your FDC or female swivel inside diameter is approx. 3 inches across, you probably need this plug. Please call or check with your local fire department if you have any questions.. . . .