Pair Scope Ring Mount Picatinny/ Weaver Rail (21mm) For 1" Tube Dia. Scope and Dot Sight Heavy Duty Double Screws Tighten each side of the Ring Cover PC. Built-in tape inside per rings to prevent from marring the scope, also prevent sliding and holding postion accurately. The Ring is for most scopes have a structure of 1 inch tube. Mid profile, 1.2" Center Height, that means the distance Between The Crosshair Center of a Scope or a Dot Sight and the Top Face of the Rail the Ring will Mounted onto. The Ring is made of air craft grade aluminum 6061 T6 and anodized Silver Finish.