Uxcell a15122500ux0253 4 PCS 15mm Diameter Fit Ball Metal Transfer Bearings Unit Conveyor Roller (Pack of 4) Product Name : Ball Transfer Unit; Material : Metal Fixing Hole Diameter : 4mm / 0.16";Fixing Hole Center Distance : 38mm / 1.5" Ball Diameter : 15mm / 0.6";Total Size (Approx.) : 32 x 21.5mm / 1.26" x 0.85"(Mad*H)