The RP Series plugs provide a general purpose, high-strength, machine thread plug adaptable to a multitude of applications. Originally designed for automotive and air conditioning tube fittings. Serrated for finger tightening, they also have a slotted hex-head for screwdriver, nut driver or wrench installation where desired. : : A:.88, B:.62, C: 1.47, D:.28, TOFITTHRSZ: 1-1/16-12.