DESCRIPTION: 2-3/4" Easy to Read Direct Reading Dial; Viewing is adjustable to 30 Degrees; 12V Night Illumination; Built-in Compensators to Easily Adjust for Deviation; Easily Installed, Fits 3" (7.62cm) Mounting Hole; Scientifically Matched Sapphire Jewel & Hardened Steel Pivot Dial Movement; Powerful DirectiveForce Magnets for Fast Heading Lock-on; High Temperature; Composite Construction for Extended Operating Range; 100% Repairable.