Martin Custom Products Re-Build kit is for the MCP Mini Lite Master Cylinder that we carry as ARC part # 3020Instructions included                       MCP Model #251
MCP Billet Mini Lite Caliper w/ Pads. 1-3/8" bore.This product will not fit the ARC 3520 Caliper Mount weldment as it is a smaller/ lighter caliper than the 3050 Caliper assembly that we offer.