50045npt, Special Cheese Bolt for Oil Pressure Switch, this cheese bolt has been specially extended, drilled & tapped 1/8"npt x 3 to accommodate 1 or more oil pressure switches which may be used for a warning light & or some some of Rally Trip Meter or some sort of monitor for a Fuel Injection system (dont laugh, we are hlping build some cars with FI for inner cities) , comes with 3 x taper plugs if you change your mind.