This Descender has a great safety reputation and is easy to use. Rope wraps around the shaft and through the device. Decelerate or Stop descent and remain suspended by applying pressure to free end of line. Lock in one position by looping free end of line over top. Preset rate of descent by number of turns around the shaft. Few turns for rapid descent, more for slower rates. Descent speed MUST be controlled by the user. 1/2" rope. Only use with L4 Nylon line.