Measure exactly before you buy - Size 01 1"/25.40mm Model MO30010 Simply 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 target Silent spring hinges won't spook game Water-tight, custom fit friction mounts anchor them to your scope Air-tight semi-O-ring keeps out dust and moisture Tested to -40 degrees F Truly ambidextrous Weigh less than an ounce