For downsizing 30mm diameter scope rings to 25.4mm (1") These extremely robust aluminium scope ring reducers permit the combination of 25.4mm (1"); rifle scopes, red dot sights, lasers, etc. with 30mm ring mounts. The reducers are made in the form of a half-shell to fit tightly and guarantee very sturdy mounting. Weight: 24g (6g per half-shell) Width: 25mm Diameter: 25.4mm (1") Material: all-aluminium Compatible with the following parts (not included in the delivery): Rifles scopes with a central tube diameter of 25.4mm (1") 30mm ring mount