Maximal Power FOUR 9 Volt Rechargeable Li-ion Batteries 9V Battery x4+Quad 4-Port Wall Charger Combo. Maximal Power 9V batteries are made with premium Japanese cell. They absolutely have no memory effect so that you can charge battery at anytime. They have Integrated microchip prevents overcharging & lengthens battery life. HIGH Capacity: 9v 550mAh (Will NOT affect battery compatibility). Maximal Power Quad 9 Volt Li-Ion Rechargeable Battery Wall Charger w/ 4-Ports for 9V Batteries is designed with a foldable A/C plug that can work with any North American Socket. Four Channel Wall Charger is designed for charging 1, 2, 3, and/or 4 batteries at a time! Quick Charge with Automatic Constant Current Control prevents overcharging, short circuit, and electronic shock. Smart LED indicator shows charging status (BLUE = Charging / OFF = Charged). Charger Type: Li-ion. Charger Specs - Input Voltage: 100-240V / 50-60Hz; Output Voltage: 8.4V-100mA4