"Leupold BX-2 Alpine HD Binoculars feature the iconic Advanced Optical System to maximize light transmission by eliminating glare-producing stray light, and maximize true light transmission for optimal clarity. The system produces premium high-definition, edge-to-edge clarity, and extends glassing time at dawn and dusk by up to 20 minutes. A large central focus dial delivers the precision focus you want when searching for deer in heavy cover, even when wearing gloves. Twist-up eyecups with an oversized eyebox accommodate hunters with eyeglasses. A lightweight yet rugged magnesium EXO-Armor housing protects optic integrity. The 1/4""-20 adapter port allows tripod mounts to be installed for use with a tripod (adapter not included). Leupold BX-2 Alpine HD Binoculars are nitrogen filled for waterproof and fogproof dependability. Advanced optical system Large central focus dial Waterproof/fogproof Twist-up eyecups Oversized eyebox Magnesium EXO-Armor housing"