This is a Blue Ranger Shoulder Pulley Exerciser that can hook on the top of your door. Its function is to aid with shoulder mobility, shoulder rehabilitation, to improve range of motion, after surgery, injuries or for ones suffering from arthritis or other impingement issues. The custom pulley has adjustable lengths, has a nylon door strap, and a metal bracket that hangs over the door. It could also be used as a strength training tool. It is new, in box.