Belkin F5X007 XM Audio System Audio system works with the Audiovox Xpress and Delphi Roady XT XM radio receivers Molded handled, water-resistant cover, and attractive ergonomic design Equipped with an integrated portable antenna for clear XM reception Powered by eight C-cell batteries or an AC power adapter Measures 18 x 9 x 5.75 inches (WxHxD)