Would anyone have any information on eBay item 264591710657?  It is listed as a dimming photocontrol. It has what looks like a pin(or a RCA plug) in the center of the standard twist lock contacts. Would this have been before the NEMA 7 pin standard for dimming photocontrols? Thanks!

I haven't seen that before on a dimming photocontrol. I did just notice though that it says it is a Demo model on the sticker on the side.