Ritchie New Sr2 Marine Venture Compass Bulkhead Mount for Sailboat Sr-2 DESIGNED primarily for sailboats 16 ft. (4.88m) to 36 ft (10.68m) in length VERTICAL Mounting Angle Through 40 Degrees. ADAPTER PLATE available to retrofit existing HV-76 and HV-77 installations (not included) CLINOMETER, protective Front & Back Covers are Included. Blue LED Night Lighting MOUNTING HOLE is 4 5/8" (118 mm) to 4 13/16" (122 mm) and 3 3/4" CombiDial THIS compass is Wheelmark Certified