A reducing bush for tapered pipe thread ports, taking a 1/2 inch NPT port down to 1/8 inch NPT. This is the biggest step in the range and is most useful when you inherit a large threaded boss in a manifold, sump, header tank or filter housing and only need to fit a small sender. Oil pressure switches, water temperature sensors, boost take-offs and vacuum ports are typically 1/8 inch NPT, so this bush saves you machining or sourcing an adapter chain. NPT threads seal on the taper, so wind on a thread sealant or PTFE tape suited to your fluid and tighten by feel rather than torque, backing off nothing once it is snug.