The Butler Creek Flip-Open Scope Cover Size 13 Eyepiece delivers premium scope lens protection with a fast flip-open design that keeps your eye on the target, while silent spring hinges prevent spooking game and a water-tight custom-fit friction mount anchors the cover securely to your scope for dependable performance in extreme conditions. This ambidextrous, ultralight cover features an air-tight semi-O-ring to keep dust and moisture out and is tested to -40F, ensuring reliable protection in cold and rugged environments; its designed for easy thumb access so you can take your shot through the narrow window of opportunity without fumbling, and its compact construction is suitable for spotting scopes as well, making it a versatile choice for hunters and shooters who demand protection, speed, and stealth from their optics.