With the Willem Elastic Door Anchor, use it for resistance for muscle building strength train. Just need to attach the Willem Elastic Door Anchor, to any door (inside and outside). Connect your resistance band and door frame. Perfect in workmanship, resistance to pressure. Its durable nylon surface will not damage or scratch surface of door or frame. How to use the Willem Elastic Door Anchor? Step 1. Open the door. Be sure to utilize a sturdy door and one that closes towards you as you are doing the exercises, (this insure that the door is actually being pulled close as you stretch the bands) Step 2. Go behind the door and thread the loop of the anchor through the opening on the hinge side Step 3. Open the loop of the door anchor Step 4. Thread your elastic(s) through the loop of the door anchor The Willem Elastic Door Anchor contains: 1x Door Anchor Willem Elastic Door Anchor specifications: Material: TPR with TPR buffer ring