Measure exactly before you buy - Size 01 1"/25.40mm Model MO30010Simply the ultimate scope lens protection for hunters and shooters. They're custom fit to your scope create a watertight airtight seal and open with a touch of your thumb so you can put your shot through the narrow window of opportunity in the most extreme conditions. Gun shown NOT included.Fast flip-open design keeps your eye on the targetSilent spring hinges won't spook gameWater-tight custom fit friction mounts anchor them to your scopeAir-tight semi-O-ring keeps out dust and moistureTested to -40 degrees FTruly ambidextrousWeigh less than an ounce