ITEM NAME:4PCS 4*13*7MM 624UU HCS U Groove Guide Pulley Rail Ball Bearings Wheel Tj Features: 100% brand new and high quality U groove Sealed Ball Bearings This item is ordinary precision, adaptation to low speed, low load applications Specification: Type: 624UU Size: (ID)4mm x (OD)13mm x (thickness)7mm U groove: 4.5mm(width), 1.7mm(depth) Material: high carbon steel Package Included:.Type: 624UU. 4pcs U groove Sealed Ball Bearings. U groove Sealed Ball Bearings. Size: (ID)4mm x (OD)13mm x (thickness)7mm. This item is ordinary precision, adaptation to low speed, low load applications.