The 52V 20Ah King Kong battery delivers reliable power for your Juggernaut Hub Duo Pro or Ultra Duo Pro. Built with premium Samsung internal cells, this replacement downtube battery provides consistent performance and extended range for long rides. Engineered to match OEM specifications, it integrates seamlessly with your existing system. An extra downtube battery makes a great option if you want to carry a battery in an additional bag and not interfere with the ability to get on and off the bike in its step-thru configuration!