Dash mount, fits standard 2-1/16" instrument hole. Ideal for power boats up to 16 feet. View adjusts up to 30 degrees to accommodate dash angle. All Ritchie compasses feature direct-read dials with night lighting, scientifically matched sapphire jewel and hardened steel pivot dial movement, and are 100% repairable. Note: X-21 series compasses do not have built-in compensators.