Butler Creek's Flip-open scope covers are custom fit to your specific scope for maximum protection. Quiet opening lids flip open at the touch of your thumb and are virtually silent. The button that opens the scope cover is ergonomically designed so that even the slightest pressure applied will open the flap, allowing you to keep your eye on the target without fumbling to open the scope cover. Water-tight friction mounts anchor the covers to your scope while an airtight semi-O-ring keeps out dust and moisture that can damage and cloud your scope. Tight flexible collar provides custom fit. Simply the ultimate scope lens protection for hunters and shooters with additional flex in the collars to fit a wider range of scopes. They're 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.