This should be the MK 5 or MC (military combat) model. The MC version is matte gray in color, not resembling stainless at all. Regardless of the actual model, there weren't many 9mm Detonics produced. I've had two and still have one. I just shot it this weekend and it's ideal for the size and weight. You'll like it. Finding magazines for it will prove to be a challenge though.
LZ