The resistance band door anchor supports your workout from any door frame and are made of strong webbing, the anchors can hold amazing weights some up to 400lbs. The hard plastic core makes sure the anchor stays put once you have firmly closed the door, make sue the door is closed as you will not be supported when the door opens. Once the anchor is secure you can create over a 200 different exercises with a resistance band, these door anchors can turn a normal door frame into a home multi gym, amazing for something that is 17 inches long and 2 inches wide. You can place the anchor in any different place in the door frame to exercise different muscles. Remember, always check by giving the anchor a check tug before use! make sure the anchor is safely secure.