The Wilwood ST Aero4 caliper shown here uses a 1.75/1.50 piston arrangement and is paired with a 1.25" rotor specification. This sizing information helps determine compatibility with existing rotors and mounting constraints, giving a clear reference for installers matching caliper piston geometry to their brake hardware and rotor thickness.
Wilwood ST AERO4 Caliper 1.75/1.50 1.25 Rotor