Mat Converter | for Performance Series MK III Pilates Reformer (Standard Profile)NOTE Reformer not included. Mat Converter must be purchased at the same time as your Performance Series MK III Pilates Reformer purchase. The platform allows one to utilize the foot end of the Pilates Reformer as a stable area from which you can push from, stand on, etc. Using the platform allows for additional exercises that can be performed on our Performance Series MK II Pilates Reformer.