FCC ID lookup is here, if you need it:
http://transition.fcc.gov/oet/ea/fccid/ — I reference that a lot.
It's interesting that they claim to have "NTC" mechanical switches. All evidence so far indicates that the switches are from Himake, which means that they were passing off Himake switches as their own, or that they owned Himake, or that they were making very similar switches.
I can't ask Nan Tan as they're long gone (part of Clevo now, apparently).
It's also interesting that they list pairs of switches side by side. My suspicion is that Ortek offered two price tiers, SX (genuine Alps) and FX (Alps clones), so maybe that's what Nan Tan were doing with the KB-6151: Alps or "NTC". But what about Omron and Futaba, being both Japanese? Why would anyone choose one over the other? Having never used a keyboard with either switch, I cannot even speculate.
(It may be that the clone switches are all unbranded for a reason: to willingly allow for companies who want to claim they made them, like Strong Man did with anything they could get their hands on that wasn't branded.)
The KB-5060N looks really nice — just add two more F keys, Windows and Fn (plus a nice Fn layer) and put an ISO enter key on it :)