Light weight aircraft grade aluminum. Works in all weather--rain,snow, heat and cold. Reusable, the only descender that will allow you, your kids and grand kids to practice using the device without having to buy a new one each time. You control your descent. It works when you want it to work, not when the device thinks it should work. In other words, if you fall on the stick side of your lock on, do you want to be able to climb back in or climb down, or would you rather bounce down the sticks in automatic mode? Ease of operation. Pull on the lanyard to come down. Release lanyard to stop. Maintenance free. Wash it with soap and water. If the arm moves, the device works.