The Sennheiser EW-D Evolution Wireless Digital System is a versatile and feature-rich system for performers who sing, speak or play instruments. With a metal housing for optimal durability, the robust bodypack transmitter, with an unobtrusive clip-on microphone ME 4 included, is perfect for daily use on stage. The EW-D digital system also allows for seamless product pairing and management via the EW-D Smart Assist App. The convenient Mobile App streamlines setup and operation without complicated menus. Automated setup creates reliable connections with minimal time and effort. Up to 2,240 selectable frequencies support up to 24 wireless systems per frequency range and preserve every detail of even the most dynamic performances up to 134dB.The Evolution Wireless Digital System delivers up to 12 hours of operation with the included lithium Ion battery pack or up to 8 hours of operation with AA batteries.