The SRAM eTap Battery charger is the only way you can charge eTap batteries. The charger is simple. It is 70mm long by 40mm wide by 27mm tall. You open up the cover, drop in the battery, replace the cover, and provided the charger is plugged in, the battery will go from empty to full in 45 minutes. There are three diagnostic lights on the side informing you about battery life and charging progress. The unit comes with a plug. Micro USB on one side, USB on the other. Micro into the charger, USB into a computer or plug. Easy, fast. The SRAM eTap Battery Charger is small enough to take everywhere, easily fits in a travel bag or a desk drawer.