Bettomshin 1Pcs 607RS Miniature Deep Groove Ball Bearings, 7x19x6mm(ID x OD x THK) Skateboard Bearings Single Side Dustproof for Skateboards Electrical Motors etc: Amazon.com: Industrial & Scientific
Many Size Bearing High-Speed Bearings for Machine or Skateboard | eBay
608RS 8 x 22 x 7 mm Deep Groove Ball Bearing, 10 Pcs 608 2RS, Double Red Rubber Sealed Ball Bearings, Fit for Skateboard Bearings, 3D Printer RepRap Wheel, Roller Skates, Inline