Watteam Powerbeat Dual Leg (L/R) Power Meter Choose between the choose between the POWERBEAT Single (single-sided), Dual (dual-sided) or 2-Pack (two full Dual Units) lightweight and easy to install; the mechanical sensor and its processing comp unit weigh less than 21 grams when attached to the crank arm  about the weight of a large bite of an apple while the POWERBEAT has all the necessary tools included in the box, with the exception of the Allen key or wrench necessary for removing the pedals No need for factory calibration or service centers - everything from installation to calibration and firmware updates is done through the user-friendly app Durable enough to sustain dust and harsh weather conditions; it even has a built-in temperature compensation mechanism, so the power figures remain consistent regardless of the weather POWERBEAT sports the industry's first ecological battery - comes equipped with a charger and the battery lasts about 60 hours