The M18x1.5 Adapter has a 1/8 NPT hole tapped in it to accept a VDO temperature or pressure sender or EGT probe. The Adapter is used for various purposes on various vehicles - Check www.MadMan.co.za for exact applications. Currently the M18x1.5 Plug fits the exhaust EGT port on Toyota Land Cruiser 1HZ Turbo Conversions (Safari Turbo)