688ZZ-4mm Small Size Bearing 688/4Z P0 Non Chrome Steel Ball Bearings 8x16x4 mm (Size : 10Pcs): Amazon.com: Industrial & Scientific
Amazon.com: KIRANDY for Desktop 3D Printer Special Bearing 688ZZ 8X16X5mm Mute Ball Bearings 688 for Kossel Mini Prusa i3 Parts 10PCS : Industrial & Scientific