uxcell 4 Pcs 15mm Dia Round Ball Metal Transfer Bearing Unit Conveyor Roller Product Name : Ball Transfer Unit;Material : Metal Fixing Hole Diameter : 4mm / 0.16";Ball Diameter : 15mm / 0.6" Mount Hole Center Distance : 38mm/1.5";Total Height : 22mm/0.87" Color : Silver Tone;Weight : 162g Package Content : 1 x Ball Transfer Unit