Keep your optics protected with the Flip-Open™ Eyepiece Cover. With a fast, Flip-Open design and silent spring hinges, you can quickly utilize your scope without spooking game. In addition, the Butler Creek® Flip-Open Eyepiece Cover is watertight and airtight. FEATURES: Fast, Flip-Open™ design Silent spring hinges Watertight, custom fit friction mounts anchor to scope Airtight semi-O-ring keeps out dust and moisture Tested to –40°F Ambidextrous Weighs less than an ounce Also made for spotting scopes SPECS: Size 13: 39.9mm