The innovative LED battery fuel gauge/charging indicator is cleverly integrated into the power button of both the Flea and Super Flea lights. Now you no longer have to guess how much battery life is left, just follow the simple color code. Green = 100% - 75%; Orange = 75% - 25%; Red = 25% - 0%. Electrical current is passed through the magnets, allowing for a compact and watertight connection. In the case of the Flea lights, it allows for mounting in both horizontal and vertical USB ports. For all electronics, please ensure only the charger provided with the original product is used for recharging its battery.