Polished Stainless Steel NPT Plug fittings. Perfect for blocking off intake manifold vacuum hole that are not being used and water pump heater hose outlets that are not being used on track cars and race engines.

Mild steel black NPT plugs are also available click here

NPT Thread is not so easy to determine like a normal bolt so use this chart and measure your engine to determine what size you will need. Most engine applications are limited to 1/4, 3/8 and 1/2 inch NPT.

Sometimes NPT threads are referred to as MPT ('Male Pipe Thread'), MNPT, or NPT(M) for male (external) threads. The taper on NPT threads allows them to form a seal when torqued as the flanks of the threads compress against each other, as opposed to parallel/straight thread fittings or compression fittings in which the threads merely hold the pieces together and do not provide the seal. However a clearance remains between the crests and roots of the threads, resulting in a leakage around this spiral. This means that NPT fittings must be made leak free with the aid of thread seal tape or a thread sealant compound - plumbers white tape