The ND-3 x40 Laser Designators features a 40mm lens and is part of the precision optical lighting instruments using advanced green laser technology. Its patented Rotary Optical Collimator uses a system of 9 fully multi-coated lenses that allows full adjustment and control of the beam diameter and intensity to focus light where you need it most. Rotating the collimator to minimum, it creates a bright micro beam of green laser light visible up to 3 miles or a planted target up to 400 yards. Rotating the collimator to more open settings provides plenty of illumination for closer objects or targets. Two CR123 3V batteries power the ND-3 x40.