This is the topeak panobike speed and cadence sensor this is a simple and easy to mount cadence speed sensor for use with panobike app this intelligent sensor automatically stores ride speed and distance data with or without your bluetooth smart ready phone then simply synchronizes later the sensor mounts to any chainstay and works with any bluetooth smart enabled systems with the panobike app this sensor has a long 1800 hours of battery life and has a ipx 7 waterproof rating