I bought my first 2 to EW122 ~ 1999 workshop facilitators dance.
They still work, and all my HF are Sennheiser EW100 and EW300 Series.
Excellent reliability, long range, extremely rare stalls, a thousand frequencies still to cram 10 or 15 HF carefree despite the various transmitters and jammers ... They operate with two 1.5V batteries or 1.2 V (only the older models used a 9V battery, I still have!) And the only failures were deplorable antennas and connectors. .. as always.
The connection level, the damn mini-jack screw is the only negative point of this UHF system: it always ends in the long run by be crunches and replacement of mini-jacks is required ...