These kits are everything you need to convert to power disc brakes on your 1955-57 Chevy. Uses D52 GM calipers for more friction surface area and improved stopping power. 11″ GM rotors mount to factory spindles and 2 piece .375″ thick caliper brackets offer a clean and strong caliper mount exceeding GM specifications. Works with aftermarket 14″ wheels. 15″ wheels are recommended