MBM PV2K-2BM - GM Bottom Mount Brass Prop Valve Kit Disc/Drum 9/16" & 1/2" Ports This is a UNIVERSAL Kit for Disc/Drum; For use with 9/16 inch 1/2 inch Ports; Bottom Mount Brass Proportioning Valve If you are thinking about upgrading your Classic vehicle with disc brakes These combination-proportioning valves are based on the popular AC DELCO 172-1353 (disc-drum) and 172-1361 (disc-disc) valves. When upgrading your vehicle from drum to disc, these small items are a must. These components ensure proper fluid transfer and contain a residual pressure valve for proper braking feel. These valves contain a low pressure shut off valve and warning light switch to ensure driver and vehicle safety should your brake system lose hydraulic line pressure. Aftermarket imported master cylinders with built in adjustable proportioning valves DO NOT feature this and could put you and your vehicle at risk. To further your decision, this Brass prop valve includes the mounting bracket, master cylinder hook up lines and a brake light warning switch for smooth install and operation. Best believe this Brass proportioning valve is far superior to most others on the market. No need to read long pitches , please view the items specifications and rest assure this is the best universal Brass Undermount Prop valve on the market.