Metal MaterialMetal Riser Block for Telescope Refractor Ring is made of aluminum alloy, lightweight and sturdy structure FeatureBuilt in grooves for mounting on the dovetail rails and aluminum material ensures light weight and enhanced durability FunctionThe risers lift your entire telescope and increase the clearance above the dovetail bar, balancing the entire system on the mount M6 and 1/4 HolesThe holes can accomodate M6 and 1/4" screws M6 and 1/4 ScrewsProvide M6 and 1/4 long and short screws for telescopes rings and dovetail plate from different brands Size Chart:1.9cmx2cmx3.6cm/0.75inchx0.79inchx1.42inch Package Includes: 1 Riser Block 2 Screws Note: Please allow slightly errors 1-2cm/0.39-0.79inch differences due to manual measurement.