Features: Brand new and high quality Double track track, more stable than single track version and wheel motion. The height remain unchanged. Use as many original sheets and part as possible. Quick installation and Upgrades. Please note that these adapters require the MGN9H rail of 3. The required length is 300MM. For the 3 option, you need to print additional Yaxis restriction block to complete the assembly. Please make sure to contact us to obtain the document, leave email when placing order. Applicable to: 3 . Specifications: Component: Metal Style: Without Guide Rail, With Guide Rail Package Includes: 1Set Xaxis Linears Rail Guide Kit note: Please allow 0-1cm error due to manual measurement. makes sure not mind before bid. Due to the differenceS between different monitors, the picture may not reflect the actual of the item.