A few years ago when I was in a wheelchair I received a Powerchair. It was great! It could go 7mph. Outside our house at the time we had a ramp built which lead to our driveway that was sand. Being adventurous one day I took myself outside and decided to go down the ramp. Needless to say the chair didn't stop until it hit the soft sand. After being thrown 10ft out of the chair into the sand I figured out what the seatbelt was for.