Rather well built for the price, this set seduced me! It is fun to make mini-dolly with that! Screen printing of the base is of no use, since masked in part by the axles. 8 with ball bearings (Chinese), rolling is soft. But attention to the smallest gap or any allowance on the "track": tremors guaranteed! Unable hence tiles, old wooden floors, exposed concrete or asphalt if we want beautiful well spun images. There's no air suspension! ; O)) But the "magic arms" with the small of the back, looks like Brassens, "that's a find!" Ideal to place your camera (or other) in the selected position! That I can not do without me. Provide a small "break" to ensure a smooth and uniform tightening. On this subject see my review for the 11-inch arms. It's all good. Glop, glop!
