The GoFit Rubber Resistance Training System lets you purchase items separately to create your own ultra-effective workout. As training progresses, one may simply expand their system with more resistance options. For example, use one Door Anchor with a variety of Tubes or Bands depending on the particular workout. All components use a universal carabiner connection, so Handles, Door Anchors and Ankle Straps connect to Resistance Tubes and Bands in a snap, for an ultra-flexible training program. The GoFit Rubber Resistance Training System— Modularly packaged and merchandised to work together as a complete component system.