With the 4-piston Dominion A4, Hayes has developed a new disc brake especially for trail, enduro, downhill and E-MTB applications.
High braking power with 4-Piston: Disc Brake Dominion A4 from Hayes
Dominion’s master cylinder is factory tuned for the shortest dead stroke possible and a crisp bite point. The Dominion A4 caliper utilizes four pistons in the most structurally rigid design possible. It features a cold-forged caliper and KingPin structural pad retention bolt that increases stiffness.