Amazon.com: KIRANDY for Desktop 3D Printer Special Bearing 688ZZ 8X16X5mm Mute Ball Bearings 688 for Kossel Mini Prusa i3 Parts 10PCS : Industrial & Scientific
uxcell 688ZZ Ball Bearing 8mm x 16mm x 5mm Double Shielded 688-2Z 2080088 Deep Groove Bearings, Carbon Steel (Pack of 20): Amazon.com: Industrial & Scientific