The Sennheiser EW-D AB (S) (article 508875) is an in-line antenna booster for Sennheiser's Evolution Wireless Digital (EW-D) systems, S frequency range 606 - 694 MHz. It sits in the antenna line between a remote antenna and the EW-D receiver or antenna distribution, compensating for signal loss over long antenna cable runs so that a receiver rack can be placed further from the stage without losing range or reliability. EW-D itself is a UHF digital system offering up to 90 channels in 56 MHz of tuning bandwidth, a 134 dB input dynamic range and set-up via the Smart Assist app. Use the booster only with EW-D equipment and antennas in the same S frequency range, and check local frequency regulations. The unit weighs about 173 g and measures roughly 125 x 85 x 30 mm.