8 inch dual power booster, 1-1/8 inch bore master disc/disc (Zinc) Compact-10 Series 8" Dual Diaphragm zinc plated power brake booster. This 8" GM truck brake booster is hand polished before a zinc finish is applied for a top quality finish. The 1-1/8in Bore master cylinder and proportioning valve is ideal for most 4 Wheel Disc brake applications.The Compact-10 mounting bracket and push rod assembly is a direct fit to your factory firewall. The Compact-10 series boosters are designed to mount closer to the firewall at a more natural angle than a factory style booster. This type of mount gives you the look & brake performance you want out of your truck. The included proportioning valve is for disc/disc applications. New unit not remanufactured Includes brackets and pushrod .