Excalibur's Insight Scope Level quickly attaches to nearly any scope and helps keep the crossbow level for consistent shot to shot accuracy; Be ready for an accurate hunting performance; This versatile Insight scope level fits all scopes with diameters from 1.495"- 1.635" (38 mm-41.5 mm); Including Excalibur's Overwatch, Tact-100, Tact-Zone, Dead-Zone, GRZ2, SMF, Shadow-Zone, Vari-Zone, Drop-Zone; Excalibur Insight scope level has a lightweight, unique design; It can quickly and easily be installed on the scope making the level visible through the scope using peripheral vision; Upgrade your crossbow hunting by increasing shot accuracy with Excalibur Insight Scope Level; Crossbow Hunting with Excalibur equipment provides the utmost performance and durability