Industrial-grade standard SBR block, with high precision linear bearing inside. Surface silver plating treatment, beautiful anti-rust, hardness can as high as HRC62, more durable. The adjusting handle can adjust the tightness of the slider. Standardized processing, perfect for guide rail positioning. Perfect 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:2100g 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: 2 x linear guide 4 x Linear bearing slider 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.