powertap-c-1-52-36-chainring-with-sensor
powertap-c-1-52-36-chainring-with-sensor, Double Chainring combination with power sensor easily mounts onto your existing crank, see compatibility chart before ordering.5 bolt, 110 BCD compact designCompatible with both ANT+ and Bluetooth SmartOver air firmware updatesCR2032 Battery included200 hour battery life310 grams