They work great and will allow you to dim the lights without introducing noise.
They are $120 new, I'll sell them for $80 (I'll pay shipping inside the US) or $70 and you pay the shipping anywhere else. (they're kinda heavy)
I bought them from mouser.com and here is the part number: 5874-291
If anyone is building a studio in LA I have 3 prehung solid core doors available and some slot resonators that I'm sure could be reassembled.
Actually you could just come by and salvage anything you see.
If I can get them out of the walls I'll probably be offering a few snakes/panel boxes that terminate in the control room side w/ db25 connectors. If anyone is interested, please let me know.