There's also a "generic make" flash sold as the Sakar / Digital Concepts 952AF/PEN, Soligor DG-420 Z, Dörr DAF-42, and perhaps other names. The Vivitar DF400MZ, Bower SFD926P, and Praktica Exakta DPZ 38AF look similar but claim slightly smaller guide numbers. Given anecdotal reports that the Sakar / Digital Concepts model is somewhat underpowered, it's entirely possible that they are just being more honest — and in fact, some empirical testing indicates that the guide number is even lower than that.
The Opteka EF-600 DG Super looks very similar as well, but doesn't come in a Pentax version — and that one makes any even stronger claim about the guide number, which Opteka says is 45m at 85mm. (There's no relation to Sigma, despite the extremely similar naming scheme.) There's a model called the Lexus / Riva SB-3000AFP apparently sold exclusively in Singapore.
It's entirely possible that the only connection between all of these models is that they're made in the same factory in China — perhaps to varying specifications, or perhaps all from the same mold.
Many newer versions of this flash have P-TTL support, but older versions do not. I am not aware of a good way to tell which it will be without testing, and I don't think an upgrade is available. The Praktica / Exacta 38AF models are quite certainly all too old, and it seems likely that the Bower and Vivitar branded models (which appeared more recently) are all the new design. Soligor has confirmed that their model uses P-TTL.
Either way, they don't have high-speed sync or work as P-TTL optical wireless slaves.
