The SpeedPuck is designed for long-term reliability in a saltwater marine environment. The SpeedPuck's caseback screws on and off like the lid of a leak-proof water bottle to reveal the battery compartment. In addition to this, the battery compartment is completely sealed off from the rest of the device's electronics, providing a second layer of protection against moisture. The SpeedPuck combines a high-accuracy GPS speedometer, compass and bar graph wind shift indicator in a compact, durable package. It is designed to be mounted on a dinghy or handheld when hiking on a sportboat. The SpeedPuck improves your sailing by allowing you to quantify the effects of boat trim, sail trim, wind shifts and current. No more second guessing yourself. • Speed and Heading updated twice a second.• Compact, low-profile design.• Maximum speed recall.• Bar graph for lift / header indication.• Waterproof to 3 m.• Can be handheld to read when hiking on a sportboat or boat mounted on a dinghy.• 20 hrs of battery life and GPS data storage.• Fully compatible with Velocitek SpeedPlay .Main Display Modes • Speedometer: Displays speed, updated at 2Hz.• Compass: Displays heading / course over ground, updated at 2Hz.• Maximum Speed: Displays maximum speed attained since the device was turned on. Bar Graph Lift / Header Indicator• Automatically locks on to your tack angle.• Bar graph shows lifts and headers in 3 degree increments.• Automatically resets when you tack or jibe.• Can be disabled if prohibited by class rules.Technical Specifications• Speed Accuracy: ±0.2 Knots• Heading Resolution: 1°• Display Update Rate: 2Hz (once every 0.5 sec.)• Water Resistance: ipx-8 to 3m / 10 ft• Display: 27mm / 1.06” digit height 120 degree viewing cone• Data Logger: Lat, Long, Time, Speed, and Heading recorded at 0.5 Hz (once every two seconds)• 30 hour of capacity• 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" thickness.• Weight Including Batteries: 295g / 0.65lb• GPS Chipset: u-blox LEA-4A• Warranty: One year