A power cage (also known as a power rack, squat cage, or squat rack) is an item of weight training equipment esigned to allow for a safe free weight workout using a barbell without the movement restrictions imposed by equipment such as the Smith machine. Originally described as an "apparatus for use with barbells," the power cage was patented in 1987 by Karl I. Mullen of Portland, Oregon. As described in his patent, and paraphrased below: