All these models below feature a 42 mm objective lens, improved light transmission from the new Flouride glass and water repellent AquaDura lens coating. Your LEICA GEOVID HD is built to accompany you through thick and thin. The housing is made of cast aluminum not only to reduce weight but also for its special robustness. It is filled with nitrogen to eliminate fogging of the lenses. The precise processing, typical of Leica, also guarantees that a LEICA GEOVID HD remains fully operational even during the most inclement weather - even down to 16.5 ft (5m) deep in water ! Its folding lines and ergonomic design make the Geovid HD extraordinarily compact and space-saving.