Rudder Position IndicatorAwareness of the rudder angle is an important safety factor. This is especially true while moving in and out of your berth, drawing alongside another boat, picking up a skier, mooring, or any other "close call" situation. Davis&'; Rudder Position Indicator gives instant visual reference of rudder angle.The pointer swings a full thirty degrees with each revolution of the wheel. Mounts directly to your hub (approximately 2" (5 cm) in diameter) with a self-adhesive pad . Rugged, hermetically sealed, weatherproof, and sunproof housing ensures long life. No cables, adjustments, or electricity required; gravity power makes it simple and service-free. Suitable for boats with mechanical and single station hydraulic steering systems. Specifications: Instrument Function: Wind Box Dimensions: 1"H x 5"W x 8"L WT: 0.1 lbs UPC: 011698038503 Owner&';s Manual (pdf)