I bought this for my RC 8, which I sold a couple of months ago.
Includes a 12v power inverter, plus a 240v/12v power supply.
The illuminated diameter is about 220mm, or 8 ¾ inches.
Flat subs of ~0.5sec give pixels ~50% brightness using my cameras.
Purchased directly from Gerd Neumann in Europe about 5 years ago.
New cost posted is 197 Euro (AUD $312).
The inverter is a bit knocked about and has some tape securing it together, so I have reduced the price accordingly. Can also be used on smaller OTAs.
Selling for $160 plus postage. Please send a PM if interested.