DECRIPTION: 2" (5.08cm) Direct Reading Dial; Easily Installed, Fits Standard 2-1/16" (5.50 cm) Instrument Hole; View Adusts up to 30 degrees; Scientifically Matched Sapphire Jewel & Hardened Steel Pivot Dial Movement; Exclusive Built-in Green NiteVu Lighting; High Temperature Composite Construction for Extended Operating Range; DirectiveForce Magnets. NOTES: X-21 Compasses do not have Built-in Compensators; Comes standard with 12V lighting. Some custom built OEM models may have different lighting.