Butler Creek Flip-Open scope covers are the best protection system in the world. They are used extensively by the top shooters, military snipers and hunters. Flip-open covers are completely weatherproof and keep rain, snow and dust off your expensive optics. The secret to good optics is the series of coatings that enhance light transmission through your lenses. Flip-open covers keep harmful debris from scratching or abusing these lenses. The Flip-open system includes an ocular cover with a red button and an objective cover with push tabs. These covers open in an instant with the push of your thumbs, they spring up and out of the way quickly and dependably.