[Size] - Wheel Size: 22x8mm / 0.87x0.31 Inch(ODxTHK); Thread Size: M6x8mm [Groove Size] - U Groove Width: 6.5mm / 0.26 Inch; U Groove Depth: 3mm / 0.12 Inch [Material] - The bearing roller is made of nylon, and the threaded rod is made of metal [DIY…