Great upgrade from the standard clamps included with cnc 3018 /cnc 3040 series and other DIY CNC's. It can be used on the MDF spoildboard and the aluminum spoildboard that fits the size of the M6 -slot nut. Working range: The clamp accommodates materials up to 40mm thick and features easy to tighten knobs for quick installation or removal of stock material. Sturdy Quality: Constructed of High Strength Aluminum Alloy with high durability and wear resistance. Versatility: Spring loaded and capable of exceptional clamping force, this is a perfect addition to any universal -track system configuration or assemblies. It is ideal for work holding, positioning, and fixturing for woodworking or metalworking, including routers, drill presses, CNC, table saws, jigs, panels, vertical mills, and more. The actual product may have slight color difference or difference, which not affect the use Colour:Silver Material:Aluminum alloy Package Contents: 4x Mini Hold Down Clamp 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.