WMS 40 PRO Handheld Wireless System features the unique HDAP (High Definition Audio Performance) technology that ensures the best possible, realistic sound at any time. The rugged handheld transmitter with its soft-touch finish is extremely easy to use and fulfills the highest esthetic requirements. The transmitters operate for 30 hours off a single AA size battery, saving frequent battery replacements and thus money. The WMS 40 PRO Handheld Wireless System includes the SR 40 Single, and the HT 40 transmitter.