I have two replaced knees... I love to restore old cars. Therein lies a problem. Two years of struggling getting down to my shop floor, and, trying to get back up. Wasn't pretty. I tried so many different work-arounds, even trying to modify some medical devices. Then I came across a video of the Aerocreeper, and was ecstatic that someone had created a solution. I had to wait till Christmas, but once the box was opened, and the creeper on the floor, I truly felt I had regained part of my life. This is the motorized creeper. I can sit down on it at a normal regular seat height, and in four seconds be flat on my back. Return to full upright is the same, where it is fully comfortable to stand erect, with two bionic knees. You can go down slow, or go down fast. But at no time do I feel out of control. This thing is so well designed and engineered. Quality of manufacture is stellar. If anything it is overbuilt. Sure see this as my new most useful tool. Its not a proprietary power system. Regular Milwaukee batteries, so if I want another (the unit comes with two, and the charger) - easy to get. Cant be more pleased.