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 thumbs, so you can put your shot through the narrow window of opportunity in the most extreme conditions. Fast, flip-open design - keep 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 -40AdegF. Truly ambidextrous. Weigh less than an ounce. Also made for spotting scopes.