Ball bearings, 3/4/5/6 mm inner diameter 10/13/16 / 19 mm outer diameter double-sided rubberised deep groove ball bearings made of steel (625-2RS) : Amazon.de: Business, Industry & Science
uxcell 606-2RS Deep Groove Ball Bearing 6mm x 17mm x 6mm Double Sealed High Carbon Steel Z1 Bearings 8pcs: Amazon.com: Industrial & Scientific
625-2RS Bearing 5x16x5mm Double Rubber Sealed Miniature Ball Bearings 625RS for VORON Mobius 2/3 3D Printer (Pick of 10Pcs): Amazon.com: Industrial & Scientific