GPS speedometer for sailing and other applications. Big numbers, easy to install, accurate, waterproof. Includes speed, heading, maximum speed and automatic shift tracking. What’s Included: Velocitek SpeedPuck USB Cable Sticker Quick Start Guide Lanyard Mounting Cradle Technical Specifications Speed Accuracy: ±0.2 Knots Heading Resolution: 1° Display Update Rate: 2Hz (twice a second) Water Resistance: 3m / 10 ft (IPX8) Display: 27mm / 1.06” digit height 120 degree viewing cone Data Logger: Lat, Long, Time, Speed, and Heading recorded every 2 seconds, 20hr capacity. Data download is compatible with Mac OS X and Windows Data download requires Windows XP, Windows Vista, Windows 7 or Mac OS X 10.6. Batteries: 3 x AA, 20+ hour endurance, rechargeable or disposable Dimensions: 115mm / 4.5" diameter, 27mm / 1.06" thick. Weight Including Batteries: 295g / 0.65lb Warranty: Two years