Item Name: HGR20 Linear Rails with Sliding Block Material: Steel, Bearing Steel Sliding Block Type: Square, Flange Measurement System: Metric PCs in Item: 1 PC Manufacturer: DLX Motion Control, China Reference: Linear Guideway Buying Guide Compatible with HIWIN series products. Refer all specification in HIWIN: https://www.hiwin.us/wp-content/uploads/Linear_Guideway-E-1.pdf