GMA 100 Rear Brake Caliper Kit For Harley FL / FX Features: Big Twin Rear, 1973-80 Fits all 4-speed, square swing arms with 10 rotor, from 1973-80 Hardware, machined aluminum bracket, fittings and axle spacer are included Axle spacer fits between bracket counter-bore and swing arm Kit requires 5/8 bore master cylinder