4-wheeled bladed edger

Southern lawngrasses are running grasses, not clumping grasses. As such, they spread out over sidewalks and curbs at a much faster rate than grasses suitable for Northern lawns. I have a battery-powered edger from Ryobi, but it has only two wheels, so having to always hold it up and keep it balanced makes it tiring and tedious to use. If you made a 4-wheeled, bladed edger, you would have a big market for it in the South.