The STIHL ADVANCE X-Flex battery bag is part of the STIHL ADVANCE X-Flex modular harness system. This bag makes it possible to conveniently carry a battery from the STIHL AP System on the STIHL ADVANCE X-Flex waist belt (sold separately). To securely fix the AP battery in the bag, a rubber strap can be pulled over the battery. In addition, the upper edge of the bag is rounded to make accessing the battery easy. Openings on the underside allow dirt and water to escape.Attaching to the STIHL ADVANCE X-Flex waist belt is easy thanks to the robust STIHL attachment clips developed by STIHL.