3x9x4 Shielded Miniature Bearing Pack of 103 x 9 x 4 Shielded Ball Bearings Lot of 10 Bearings 3 x 9 x 4 Shielded Ball Bearings, the inner diameter is 3mm, outer diameter is 9mm and the width is 4mm, Bearings are made of Chrome Steel each bearing has 2 metal shields to protect the bearing from dust or any possible contamination, also bearings are pre lubricated with grease. Item: 3 x 9 x 4 Ball Bearings Type: Deep Groove Ball Bearings Closures: 2 Metal Shields Lubrication: Self Lubricated