Abstract: A lens cover for a firearm scope comprises a lens ring configured to mount to a lens, a cover bracket pivotally mounted to the lens ring, and a cover membrane disposed upon a portion of the lens ring and a portion of the cover bracket. When the cover bracket is in a closed position, the cover membrane creates a seal against the lens ring. The lens ring comprises an elastomeric material so as to enable mounting of the lens ring to lenses of differing diameters. The cover bracket includes a plurality of opposing mounting holes for selectively mounting the cover bracket to the adjustable lens ring.