Sennheiser EW-DX SK S1-10 Beltpack Transmitter (606.2 - 693.8 MHz)

Although not fully used yet, the testing done was top rate. Construction superb, all but the battery door is metal so will resist the odd bump or two. Unique is the display showing the state of the transmitter WITHOUT battery power, which I was aware of having read up on this item. Syncing with the receiver, via Bluetooth, was straightforward. You have to press the transmitter's syncing button BEFORE the syncing button on the receiver.