This model uses a true sighting optic that allows you a direct read of the internal compass card housed in the fluid filled capsule. The vertical lubber line of the sighting optic lets you take full advantage of the 1 degree resolution used on the compass card,The clinometer allows the measuring of differences in height and slopes. Great for hunting, hiking, Geology and other outdoor activities. Foldable metal lid Sighting window with sighting line, Floating compass dial with 360˚ scale, Luminous magnet arrow Adjustable prism lens This compass is a precision instrument, the deviation of 1 degree or less Minimum score value. Description: Material: High-strength Engineering Metals, Army Green Paint Working temperature: - 20 C ~ + 50 C Fluorescent dribbling fluorescent display. Note:Light shooting and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3 cm.