This compass series is for fast runabouts bass boats center consoles and sport boats. Flush mount type white case. Features include built-in compensator magnets 12V DC night lighting jewel and steel pivot movements and movable sunshades. 2-3/4´´ apparent direct-reading cards.SPECIFICATION:2 3/4 Easy to Read Direct Reading DialEasily Installed Fits 3.75´´ (9.53 cm) Mounting Hole.Internal Green Night IlluminationBuilt-in Compensators to Easily Adjust for DeviationScientifically Matched Sapphire Jewel and Hardened Steel Pivot Dial MovementPowerful DirectiveForce Magnets for Fast Heading Lock-onMovable Sun ShieldHigh Temperature Composite Construction for Extended Operating Range100% Repairable5-Year Ritchie WarrantyZone: One (1)Boat Style: PowerboatAll Magnetic Compasses are vulnerable to magnetic interference which will produce errors called deviation. It is the Owner/Operator and/or Helmsman´s responsibility to make sure the compass is properly installed and compensated. Compensation is the act of correcting for deviation. Magnets (speakers microphones etc.) ferrous metals (steel iron etc.) and current carrying devices are common causes of deviation. It is important to understand that magnetic compasses point toward Magnetic North. There is a difference between Magnetic North and True North and that difference is called variation. Variation differs depending on your geographical location and can be determined by referring to a local chart.PRODUCT NUMBER: FO-3225