Industrial-grade standard block, with high precision linear bearing inside. silver plating treatment, beautiful anti-rust, hardness can as high as HRC62, more . The adjusting handle can adjust the tightness of the slider. Standardized processing, for guide rail positioning. for your DIY CNC routers, mills, lathes. Aluminum alloy support rail with pre-drilled holes for ease of mounting. Type: Linear slide guide Glide path: linear guide Rated dynamic load: 860 Rate static load: 1370 Precision grade: H Fixed bolt size: 8 (mm) Fixed mode of sliding block: Locking type Allowed static torque: 1 (kn.m) Weight:4200g colour:Silver Material:metal size: Linear Slide Rails- 500mm / 19.7inch (Length) x 12mm / 0.47inch (Diameter); Linear Bearing Side Blocks -40mm x 40mm x 28mm/1.57 x1.57 x1.10inch( Length x Width x Height) Package Contents: 4 x linear guide 8 x Linear bearing slider Only the above package content, other products are not included. Note: Light reflection 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.