does anyone know what the difference between the SDR and the SD Bazzaz units are?
I know the SDR has a catalog number of F590 and the SD F590-1, but can they be used interchangeably?

from Bazzaz's site



I ask as the ebay pricing is better than most and all I see are F590 units that claim to fit SD.

TIA

I don't know the difference, but you should call Bazzaz and ask for Chris. He should know the answer.