Need extended court time from your Elite Series machine? The external battery pack will provide you with an additional 4-8 hours of court time. The external battery pack includes a large 18-amp sealed lead-acid battery, battery cord with connector, XLR adaptor, 1-amp fast battery charger, and canvas carrying bag with shoulder strap. The external battery pack can be used with any Elite Series tennis ball machine. Lobster Tennis Equipment EL19