Have a Dent Engineering MK-TK/KOS1 Arrow Kart 4 Piston Caliper with Mounting Bracket for OTK Kart. Bolts right on to OTK Kart and brake lines. Uses Standard 15mm Arrow Brake Pads. New this Caliper and Mounting Bracket was $400. Can run with OTK 16×208 brake rotor or Arrow 18×205 brake Rotor. Also have 18×205 Arrow Brake Rotor and 50mm Rotor Hub which was over $260 new combined with Hub hardware. Very easy to mount on OTK Kart with much stronger brake feel. Pad life is also much longer. System works great, just don’t need it anymore.