Butler Creek Flip-Open Scope Caps features a fast, flip-open design and silent spring hinges that get you on target silently. Water-tight, custom fit friction mounts anchor them to your scope. Air-tight semi-O-ring keeps dust and moisture off your lens and caps. The rugged polymer material withstands hot and cold climates. Features:1.341" ;34.10mm;Silent spring hinges;Water-tight custom fit friction mounts anchor them to your scope;Rugged polymer material withstands hot and cold climates