This air brake relay valve with bracket is the perfect replacement part for your Mack truck's braking system. It features a 2 @ 1/2" supply port and is designed for use with HALDEX air brakes. The unit quantity is one, and it comes with the manufacturer part number KN28065. This valve is ideal for commercial truck parts and is listed under the "Other Brake Parts" and "Brakes & Brake Parts" categories on eBay Motors. It is a reliable unit type that will ensure the proper functioning of your brakes. Get your truck back on the road with this high-quality air brake relay valve.