Compatible with post-2004 riflescopes with 40mm or 50mm objective lenses (see inventory availability for correct sizes). Includes both eyepiece and objective covers. Our Alumina Flip-Back lens covers feature powerful neodymium magnets to hold them securely closed, and the triple O-ring seals provide maximum protection from the elements. Our Alumina Flip-Back lens covers feature powerful neodymium magnets to hold them securely closed, and the triple O-ring seals provide maximum protection from the elements. Constructed out of durable 6061-T6 aircraft grade aluminum, they are precisely machined to allow for quick and easy operation, and a low-profile position, when open, make these Flip-Back lens covers stand above the rest. The round objective and ocular models can be rotated so they can open in any direction.