Easy to install - no holes in deck. Uses 2 #6 non-magnetic fasteners (owner supplied). No wiring or power required. Twist on/off for easy removal. Lock-in rhumb or lay lines with CourseMinder movable bezel with heading indicator. See wind shifts & headers with racer's CombiDial & tactical quadrants. Steer magnetic course heading with CombiDial and forward lubber line. Exclusive Directive Force magnets. 45 deg. lubber lines. 4-1/4" base dia. 2" mounted height. 2-3/4" high visibility blue dial. 25 deg. heel angle.