This battery from Eunorau is the direct replacement for the original Ebike battery that snaps into the frame rail (see compatibility below). Many Ebike owners choose to have an extra battery to keep at their office or vacation home -or- they fully charge the extra battery and bring it with them if they are planning an extended journey on their Ebike. Having an extra battery allows you to DOUBLE your ride without having to take time to charge. Just like you have extra cell phone chargers stashed - bundle this battery with an extra charger to keep where you do your secondary battery charging.