Easily and securely mounted inside the seatpost the WE Battery is well protected from water or salt intrusion and provides long-term performance reliability with almost no weight penalty.Power cables run inside the seat-tube to the WE front derailleur and through the chainstay to the WE rear derailluer Centrally located on the bike to eliminate adverse handling characteristics 7.4V LI-ION battery provides around 4000 to 6000km charge life (depending on riding and shifting style) Fit and forget no need to remove for recharging Charger battery and power cables included