The pull up bar is designed with two widening anti-skid devices on both sides.It's very simple to install, just need to twist both sides to get it to the length by useing our Hex Wrench. We design our half arc structure through the leve principle,so that we are very stable and can bear the maximum weight,When mounted properly, this fitness bar can hold up to 440lbs(200kg), giving you full support for pull ups and chin up.The pull-up bar can fit in most door frame between 28.35"- 36.2" adjusted by the Hex Wrench.t can be installed in any cement walls, security doors, solid wood doors, corridors but not including fragile door frames,Suitable for standard doorway, perfect for home, garage or office use. Our home gym bar allows you to perform a variety of upper body strengthening exercises. You also can move the upper body workout bar down to the lower part of the doorway for sit-ups, push-ups, dips, crunches and even stretching. You are not necessary to go to gym to waste your time and expensive membership fee! The pull-up bar is easy to carry and easy to install. use the pull up bar also be a good offer to attain your workout results. Strength training target any muscle including arms, legs and Abdomen. Keep fit and get your dreamed body at home gym.