Ritchie F-50 Explorer Compass - Flush Mount - Black 2-3/4" Easy to Read Direct Reading Dial Easily Installed, Fits 3.75" (9.53 cm) Mounting Hole. (NOTE: Be sure you print the template Actual size) Internal Green Night Illumination Built-in Compensators to Easily Adjust for Deviation Scientifically Matched Sapphire Jewel & Hardened Steel Pivot Dial Movement