MULTIFLEX Flip-Open Lens Cover for a Riflescope EYEPIECE lens. These Butler Creek lens covers are completely weatherproof and keep rain, snow and dust off your expensive riflescope lenses. When you're ready to shoot, a flip of your thumb opens the cover and you're looking through a clean, dry scope lens. Protecting your lenses is important,too. Good quality optics have delicate lens coatings that enhance light transmission through your lenses. Flip-open covers keep harmful dust, debris, twigs, and dirty fingers from scratching or abusing these lens coatings.