This system features the 4-piston, S4 caliper mounted to a 11", 2 piece slot, drill, zinc plated rotor. The S4 caliper has D.O.T compliant dust and weather seals and uses the popular DR1 or HB100 pad type. Rotors are pre-assembled with NAS high grade stainless hardware. Billet aluminum hubs come assembled with premium bearings packed with Redline synthetic grease, billet dust caps and come pre-assembled on 2" drop spindles. All mounting brackets, stainless braided hoses and hardware are also included. The 11" SS4+ is designed just like Baer's larger systems, but in a smaller package for 15" wheels.