Has anyone heard of the RTR DR-1 electrostat?

I acquired one in good condition and there is very little information on it. It was made in 1980-1981 and 1986 was $3600 retail. It's the only omnidirectional electrostat element I've seen. There is no review or much detailed information about. There are a few out there and I am shocked that anyone would sell it considering most owners do not sell these. It's like the Acoustat spectra 66/6600 electrostats. No one sells the very few that were made.