Helmsman Compass Features 3 3/4" PowerDamp Flat Dial Easily Installed, Fits 4" (10.16 cm) Mounting Hole. Exclusive Built-in Green NiteVu Night Illumination Built-in Compensators to Easily Adjust for Deviation Scientifically Matched Sapphire Jewel and Hardened Steel Pivot Dial Movement Powerful DirectiveForce Magnets for Fast Heading Lock-on Movable Sun Shield 45 Degree Lubber Lines High Temperature Composite Construction for Extended Operating Range 100% Repairable Exclusive 5-Year Ritchie Warranty