Sealed Ball Bearings, bearing has rubber Seals to protect the bearing from dust or any possible contamination, these bearings are lubricated with grease, single row, radial, deep groove ball bearings, the chrome steel balls are separated by a steel cage, dimensions are 3/4" Inch ID x 47mm OD x 14mm wide, here is the 6204-2RS catalog:

• Item: Ball Bearing
• Type: Deep Groove Ball Bearing Design
• Quality: Standard Precision
• Inner and Outer Rings Material: Chrome Steel
• Balls Material: Chrome Steel
• Cage Material: Steel
• Band: VXB
• Closures: Rubber Sealed
• Lubrication: Self Lubricated (Grease)
• 6204-2RS Size: 3/4" inch x 47mm x 14mm
• Inner Diameter: 0.75" inch (Bore/ID)
• Outer Diameter: 47mm (OD)
• Width: 14mm
• Quantity: One Bearing