Wow, I wouldn't have known. So I take it that any DK that doesn't have a number in its name is a DK I, and therefore RD?
BTW, OP, when I saw your Subject line, I thought you meant someone had listed an MK on eBay and used a title implying that only switches were for sale—i.e. that it was a hidden good deal. Instead, how about something like this?:
Warning: Das Keyboard I on eBay (non-mechanical)