I neede a low support for moving appliances that could transverse small imperfections like cracks and small holes. I used eight 2 Holes Flange Ball Transfer Unit Mounted Bearings:Ball Transfer Units four on a side of a piece of plywood. this would allow three units to support the item as one of them crossed the hole. Works great. Just tilt the washer dryer or other appliances and slide the mover under it.