The Wahoo TRACKR SPEED sensor is the sleek, magnet-less solution for capturing cycling speed data. It easily mounts to your bike's front wheel hub, and the Bluetooth Smart and ANT+ dual band technology allows you to connect to and display data on both smartphones and bike computers. Tracking speed data has never been this easy. Replaceable Battery - No charging required! Operates on a coin cell battery for up to 200 hours of use. Universal Fit - TRACKR SPEED will fit with most hub sizes. Dual Band Technology - Both ANT+ and Bluetooth Smart allow for a wireless connection to both smartphones and bike computers. Visible Connection - Two LED lights show the sensor's device connection (blue) and speed detection (red). Specification Physical Dimensions: W: 3.5cm x H: 3.2cm x D: 1.8cm W: 1.4in x H: 1.3in x D: 0.7in Weight: 13 grams (0.5 oz) Battery: CR2032 Battery Life: Up to 200 hours Water Rating: IPX7 (submersion up to 1 meter for 30 minutes) Maximum Hub Diameter: 40mm Note: Spe...