Ritchie Compasses provide accuracy from the inside out. When properly sized, installed and compensated a marine compass is the most important instrument on any boat. It will provide accurate, trouble-free heading references under the most adverse conditions without relying on electricity, radio signals or satellite communications. The most important criteria when selecting a compass are dial size and mounting style. Quality components aid accuracy, smooth response, stability and trouble-free operation. Modern technology makes Ritchie Compasses the World's Best Marine Compasses.

• 2 3/4 Inch Direct-Reading Dial
• Directive force Magnets
• Extended Temperature Operating Range With Composite Construction & Diaphragm
• Package Dimensions: 6.9' ( H ) x 6.2' ( L ) x 7.0' ( W )
• Included components: Compass Owner's Documentation

The diameter of the mounting plate is 4 in. With the numbered bezel mounted, it is approximately 4 and 1/4 inches across.

Ritchie compasses are factory balanced for zone 1. So, no. You have to specifically order the zone you wish to travel. I am not aware if they do that for this (lower end compasses) or not, but you will have to go through the Ritchie website.

If you put anything like a light or a battery near this compass you won’t be able to use it as it will severely affect its accuracy and this compass cannot be adjusted as you might be led to believe in the product description.

You do need to drill two holes to mount the compass on some sort of base, but a couple strong strips of Velcro might hold it securely.