These make it easier for washing your vehicle. Don't break your back constantly lifting your bucket when you can just push them. These dollies come with bigger 3" casters which make a difference on driveways & seams. You can pick from black, blue, and red dollies. You can choose your caster color: pick from either red for gray. You'll also get some bucket tensioners that screw into the dolly and keep the bucket from moving around.