The M16x1.5 Adapter has a 1/8 NPT hole tapped in it to accept a VDO temperature or pressure sender. The Adapter is used for various purposes on various vehicles - Check www.MadMan.co.za for exact applications. Currently the M16x1.5 Plug fits the Land Rover TD5 engine sump for oil temperature measurement and the Toyota LC 1HZ Coolant elbow for coolant temperature measurement.