The EZ-Up Rack is dual bar inversion rack which mounts in your doorway. This wonderful exercise device also doubles as a chin-up bar and literally requires no floor space. This product is ideal for the physically fit athlete who is looking for a way to decompress after a workout. The EZ-Up Rack is used with gravity boots to invert at a full 90 degree angle. While inverted, you can conduct inverted sit-ups, squats, and rotational stretches. Two features of the Hang Ups EZ-Up Rack make it unique. Locking brackets ensure your safety. Our priority is your safety. There have been a few isolated incidents where children jumping up to catch the rack have un-intentionally unhooked the rack from its "U" shaped holder. The chance of this occurring has been eliminated by our snapping locking lock bracket, which is standard with all units.