Willwood dynapro 4 piston aluminum brake caliper 120-8544-SI. Piston diameter is 1.75, accepts .810 rotor. This is a new unused part in open box. This has been modified, someone has previously drilled out the pad pin bores to accept a larger pin. See pictures. Very nice condition otherwise, comes as pictured with no other hardware included. Buyer is responsible for verifying correct fitment before purchase.