The NPT (National Pipe Thread) plugs have tapered threads and sealing is done by the threads themselves. Always use a small amount of AeroSeal (AF98-2023) on all NPT threads and tighten until the it stops. These NPT plugs are ideal for sealing up ports and fittings that are unused such as unused holes in your intake manifold, or any open vacuum, coolant, or oil holes. Each plug features an internal hex which provides an easy installation and a better appearance. These plugs feature a steel construction with a zinc coated or black coated finish.
