Wilwood High-Volume Aluminum Master feature high pressure die-cast bodies from high-grade aluminum. Wilwood. High-Volume Master Cylinders have the highest fluid capacity of any integral reservoir design. With a total capacity of 8.2 ounces, there is at least 26% more fluid volume than other brands. . With 1-7/16″ of piston travel, it offers extra margin when used with large piston calipers. Heavy duty internal springs provide fast retraction. Formed steel lids with bellows type gaskets keep the moisture out. Wilwood master cylinders use common dimensions for flange or side mounting and a 1/8-27 NPT outlet port.