PRP Pro Series CAS Bracket With Head Drain Fitting - Nissan RB20/RB25/RB26PRP Nissan RB Twin Cam Engine Pro CAS Bracket With Optional 20AN Head Drain Fittings Our latest creation and evolution to our billet Cas bracket for the RB now includes a water fitting option to get water through the front of the head through its largest Welch plug hole. Ideal for dry block wet head setups ruining up to 20AN fittings but also engine needing more cooling options in though the front of the engine. The CAS bracket itself has a 16 ORB