Bosch BAT610G 18-Volt Lithium-Ion HC (High Capacity) 1.5Ah Lithium-Ion Slim Pack Battery with Fuel Gauge Unique Pack Design helps keep the battery cool even when it's working overtime Advanced Lithium-Ion technology delivers unmatched performance, and allows for a 50-Percent longer run time than competitive models Battery fuel gauge takes the guesswork out of when you need to charge Performs just as well in cold weather as in normal temperatures