Closed Curve Adapters are for are for CR Newtonian 2" format size crayford focusers. Curve adapter's bolt pattern matches MoonLite's CR off set pattern. Best for new installations where no existing holes exists, and new holes can be drilled. Please see Universal install kits for curve plates to match existing hole patterns. Matte black anodized aluminum with laser engraved size Adapters add .150" to the mounting height. Weight: less than 1 oz. Adapters are available for 6 through 24 inch OD Optical Tubes. Price: € 45 Stainless steel mounting bolts included Specify your Optical Tube Outside Diameter.