Professional Mirror Compass. The advanced navigation compass. When venturing out into unknown territory, these sighting compasses offer precision navigation with a variety of carefully engineered and dependable features for challenging conditions. 2.56 x 3.98 x .71 inch. High grade steel needle with jewel bearing. Balanced for northern hemisphere. Adjustable declination correction. Liquid filled capsule for stable operation. Mirror for sighting bearings and signaling. Sighting hole and notch for accurate bearings. Non-luminescent bezel