Topeak PanoBike Bluetooth Smart Cadence and Speed Sensor Rubber bands mount with zip ties allow quick and easy mount on chain stay or seat stay Will automatically store your data whenever you ride with or without your Bluetooth Smart Ready phone Weight 21 g/0.74 oz. Open API allows to work with PanoBike App and other Apps with Bluetooth 4.0 connection program Unique Bluetooth Smart algorithm extends battery lifetime up to incredible 1800 hours (5 years lifetime if workout 1 hour per day)