Wilwood's HD Series Fixed Mount Rotor Hats have a long standing reputation for fit, performance, and durability. HD Series hats are manufactured from premium grade aluminum alloys offering high strength, low weight, and show quality appeal. HD hats have not only been a mainstay in many of Wilwood's racing disc brake conversion kits, but they can cover a range of applications from an OE four lug axle shaft to a Grand-National stock car racing hub. HD hats feature a straight bell construction with a flanged rotor mount ring, Threaded-hole mounts for use with through hole rotors. When used with matching Wilwood rotor hardware, these hats provide solid mounting for a wide range of custom and competition disc brake applications.These features combine to provide maximum radial clearance between the caliper body and the hat. This can be a critical factor when trying to squeeze a large caliper inside a small wheel. Many hats offer multi-lug wheel patterns for added versatility. Some hats can be ordered blank for custom axle building and other unique applications. Through-hole mount hats for use with threaded hole rotors. When used with matching Wilwood rotor hardware, these hats provide solid mounting for a wide range of custom and competition disc brake applications.