The Aeroflow Nissan RB Twin Cam Head Drain Adapter is designed to help prevent potentially dangerous amounts of oil from pooling in the back of the cylinder head. Specifically designed to suit the Nissan RB twin cam cylinder head from a RB20, RB25 and RB26. This kit helps drain the oil back to the sump with a -10ORB port that allows you to plumb the drain line. Installation is easy with removal of one welch plug on the back of the cylinder head, push in the head drain and bolting it to the thread already in the cylinder head.