It's a model 21-4 "1950". Sort of an homage to the old hard hitters but not a faithful example as the purists will quickly point out.
Variations include blue, nickel, and case colored (done by Turnbull restorations for S&W) finishes in both the "1950" and "1917"-esque frames.
They were released as the 21-4 in .44 special and the 22-4 in .45 ACP.
They are in the classic series, not to be confused with the Heritage Series which, if I am not mistaken, came from the Performance center.
As far as I know, they were not well received and thus produced in relatively low numbers though many folks appreciate them for thier retro looks and high quality finish.
The "1950" was also produced as a special for Thunder Ranch and some of those bear a rather unsightly (IMO) gold TR logo.
They are excellent shooters from my experience. I own the 21 and 22 "1950"s in case color and a nickel 22 "1917. All three have stunning finishes which makes me cry every time I look at the MIM parts and lock hole.
Here is my 21-4 with a few finger prints which I've shown too many times. I haven't photographed the others - something I hope to do this winter.
I see asking prices around 1K and above on GB but they are regularly re-listed after bitd up to $900. I paid less than $600 for each...but I sure wouldn't sell them for that.
Nutshell: Functional eye candy that may someday be desireable, but I would not go so far as to call them collectable...yet.
Let us know how you make out.
A.