The rounded back fit nicely into the rounded gutter, and adjusts to the angle. In our case it could have been a couple inches wider.the 48 inch length is just a little to long to fit between car tires, and just a little bit short for most modern vehicles to put both tires on it at the same time. (our wheel base is 72 inches). So if that bothers you, you'll need to buy two of them.It definitely solved our wheelchair mobility issue making it easy to transfer from driveway to street.Solid stable construction