The Eartec UltraLite HD Wireless Headset range was introduced in July 2018.
The HD master is able to register 4 x HD Remote headsets.
Maximum transmit power 100mW.
Speech Encoding ADPCM / 32bit/s  (Adaptive Differential Pulse Code Modulation)
Frequency Range 1.9 GHZ Licence Free.
Range 300 yards (line of sight, terrain dependent)

The original Ultralite headsets, now called classic, are not compatible with the HD range.