Developing a brake with power and the right feel was the challenge. Hayes has solved it with a completely new system. The master cylinder of the Hayes Dominion A4 brake is factory-set for the shortest possible dead travel and a clean point of contact. The caliper of the Dominion A4 brake uses four pistons in a design that maximizes stiffness. It features a cold-forged caliper and a KingPin pad retention screw that enhances rigidity. With a motorsport-inspired two-port bleed system, DOT 5.1 fluid, and a Kevlar hose, the hydraulic system is designed for optimal performance at all temperatures and for easy and efficient maintenance.