The Sennheiser EW-D SK (S1-7) is the digital UHF bodypack transmitter from the Evolution Wireless Digital range, used with lavalier (clip-on) and headset microphones for presenters, actors, teachers and worship leaders, or with an instrument cable for guitar and bass. It connects to Sennheiser headset and clip-on microphones via its 3.5 mm locking input and pairs with the EW-D EM receiver. The S1-7 version covers 606.2 - 662 MHz. Like the rest of the EW-D series it offers a 134 dB input dynamic range with no sensitivity adjustment needed, 1.9 ms latency and an equidistant tuning grid allowing up to 90 channels in 56 MHz, with setup via the Smart Assist app over Bluetooth Low Energy. It runs up to 8 hours on two supplied AA batteries or up to 12 hours on the optional BA 70 lithium-ion pack. The transmitter measures 63 x 80 x 20 mm (without antenna) and weighs 120 g. Microphone is not included.