This unique spin-on adapter can get you out of the tightest situations. Most other adapters have the ports facing straight out of the engine block, which requires several inches clearance. This adapter, however, positions the ports 90 degrees to the mounting surface, requiring less than 1 1/4" of clearance from the block! The center nut is a separate part, which allows you to rotate the adapter to position the ports exactly where you need them. 20x1.5mm thread and 2 5/8" diameter O-ring fits Porsche 928 and 944, as well as many Honda applications. 1/2 NPT female ports.