KingsBox Jammer Arms with Mighty Uprights and can, therefore, be used on Mighty Rigs and racks. Since they don’t take away much space, can be left on the uprights even when not in use. Thus, will however not hinder the functionality of the upright nor the loading capacity. Due to the special mounting system, the Jammer Arms cannot damage the columns. Each Jammer arm, has at the outer end a bumper carrier, to load up the weights and therefore make training even more interesting and challenging. There are two different grips at the inside, so athletes can opt for a wider or narrower grip. If you are looking for an accessory with which you can train each upper body muscle group individually, the Jammer Arms are the perfect tool.