I imported them directly from China and they are a really good Stamford copy, I have used them for many years and they have been really reliable.  I coupled them onto the Lister LPW4 engines and they have have had no issues with them.

The specification is:

3 Phase – 415 volts – 22Kva – 50hz – 1500 rpm.

They are single bearing and have a SAE5 Adapter and a SAE 7.5 coupling disk

They are complete with phase switchable ammeter and voltmeter and also have a Hz meter.

They also have an main isolator switch