Elite Optical System offers excellent dawn-to-dusk light transmission for a bright image, elite-level glare reduction in harsh light, and the resolution and clarity; A built-in 1/4-20 rotatable tripod adapter port makes it easy to mount to a tripod; Ergonomic design ensures Leupold's products are slim, lightweight, and fit well in your hands no matter what size they are; All-day glassing comfort with increased contact area, and a flexible ergonomic design; Features an extremely smooth focusing system for fine adjustments; Removable twist-up eyecups allow you replace them in the field if damaged; Line of Sight (LOS) calculates the distance to a target in a straight line, regardless of any incline or decline; Bow Mode uses the distance and the angle of a shot to calculate a ballistic equivalent to the target for more accurate uphill and downhill shots; True Ballistic Range (TBR) technology provides ballistically calculated ranges for extremely accurate shots at longer distances and steeper angles; Waterproof and fogproof