Works longer - up to 65% more run time</br>CoolPack Design technology - innovative pack design dissipates heat for 2x recharge life</br>Optimized cold weather performance?? down to -4 degrees F / -20 degrees C</br>Integrated battery fuel gauge</br>Electronic Cell Protection (ECP) - prevents cells from overheating?? overloading and deep discharging</br></br>Product Description</br></br>Design and build your very own Bosch 18 V combo