Nikon Monarch 5 3-15x42 ED SF Advanced BDC Riflescope 3-15x Magnification; 42mm Objective lens Massive ocular lenses deliver a huge, exceptionally bright, high-resolution sight picture and constant, non-critical eye relief that can be used on even heavy recoiling rifles Fully multi-coated lenses for bright, vivid sight pictures and optimum light transmission from dawn to dusk Optimized for use with Nikon Spot On Ballistic Match Technology. Spot On allows you to discover all of the exact aiming points on your scope's reticle at various yardages for your specific ammunition and load Nitrogen purged and O-ring sealed for complete waterproof, fogproof and shockproof performance.