ITEM NAME:2 pcs LM4UU 4mm Bore Double Side Rubber Seal Linear Motion Ball Bearing Bus W4Q4 2 pcs LM4UU 4mm Bore Double Side Rubber Seal Linear Motion Ball Bearing Bus W4Q4 LM4UU 4mm Bore Double Side Rubber Seal Linear Motion Great for linear motion on 3D printer, cnc, and other applications. These ball bearing with two rubber dust sealed to prevent ingress of dirt, water and foreign matter. Smooth moving, low friction, high rigidity and long life. Economical, easy to maintain replace. Product Name: Linear Bearing Material: Bearing Steel Color: Silver Tone Weight: 7g Model: LM4UU Outside Diameter: 8mm Inside Diameter: 4mm Length: 12mm Package Content: 2 * Linear Bearing Only the above package content, other products are not included. Note: Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm..LM4UU 4mm Bore Double Side Rubber Seal Linear Motion. Model: LM4UU. Great for linear motion on 3D printer, cnc, and other applications. 2 Linear Bearing. These ball bearing with two rubber dust sealed to prevent ingress of dirt, water and foreign matter.