Ideal for both power and sail. Large 4 1/2 dial with large numerals for easy reading. Flat-open card style. Navigator Compass Features 4 1/2 PowerDamp Flat Card Dial with Large Numerals Easily Installed, Fits 4.75 (12.07 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 Construction for Extended Operating Range Custom Fitted Protective Covers Available 100% Repairable Exclusive 5-Year Ritchie Warranty