The Ritchie 4-1/2 inch Navigator compass is designed for sailboats 28-45 feet in length, and feature built-in dual 12 volt Nite Vu lighting. Compass has a built-in clinometer to tell how much your boat is heeling. Internal gimbal system provides maximum stability during extreme pitch and roll conditions. A scientifically matched sapphire jewel and hardened steel pivot dial allows for smooth movement and accurate readings. Compass has 45 degree lubber lines and built-in compensators adjust for deviation.