PERFORMANCE PIN High Performance Weight Stack Pin Instantly transforms compatible selectorized equipment into "variable resistance machines". Allows trainees to "pre-select" multiple weights to be used DURING a set. Nothing to install or attach to equipment. Portable, effective, convenient, durable,reliable! Can be used by anyone training on compatible selectorized equipment that accepts 4"L x 3/8"D selector pin at home or the gym. 2/package. Proudly made in the USA, Patent pending.