A 1/8″ NPT socket plug for closing off unused tapered pipe ports. This is one of the most common port sizes on engine blocks, manifolds, fuel rails, adapter blocks and pump housings, so it is the plug most often needed when a sender, gauge or vacuum take-off is relocated or deleted. The internal hex socket lets it sit flush in shallow bosses and recessed ports where there is no clearance for a spanner. NPT threads seal on the taper, so apply thread sealant or PTFE tape and tighten to finger tight plus a turn or two rather than leaning on it.