Four sets of Shure PSM 600 wireless in-ear monitors, receivers and transmitters. These were really expensive units 20 years ago and work fine, but......
This 600Hz waveband has been discontinued for public use.... whatever that means. I'm not sure if it's much or an issue up here in the north country, more an issue in urban areas, but it is what it is. So let's consider this a 'Parts Only' situation.