Wilwood’s newly designed GS model compact master cylinders have been fully retooled using advanced high pressure die-casting processes to create a lightweight body design with consistent internal grain structure and cross-sectional wall thickness. An all-new rebuildable internal piston and return spring assembly creates a quick and positive release for improved durability and extended service life. The new die-cast aluminum bodies feature a protective E-coat finish, and are individually laser engraved for easy identification of the bore sizes and threaded connections. The remote reservoir model lineup has been expanded to include .50” and .81” bore sizes. Integral reservoir model twist-on caps have been upgraded with a positive seal, pressure balancing bellows-type gasket to keep fluid in and moisture out.