MGN12H Black Miniature Linear Rail Guide12mm Width Slide Block (300mm) Features: This linear rail and block are small in size and lightweight, especially suitable for small equipment. Adopting 4-point contact design, it can bear load from every direction, and has good strength and high accuracy. Designed with ball retainer, which allows interchangeability in the case of allowable precision. Slide block is designed with mini retaining steel wire, and the steel ball will not fall off if taking the slide block down. Widely used for automatic equipment, precision measuring equipment, and many other machines that need precision linear movement. Specification: Model: MGN12H Type: Slide rail Slide track: Linear rail Length: 250mm / 9.8in, 300mm / 11.8in, 350mm / 13.8in, 400mm / 15.7in, 450mm / 17.7in, 500mm / 19.7in, 550mm / 21.7in (Optional) Width: 12mm / 0.5in Material: Bearing steel Precision class: H Block Fixation Method: Locked Weight: 217 ~ 416 g / 7.7 ~ 14.7 oz(approx.) Package list: 1 * Linear Guide Rail  1 * Linear Guide Block