I had a guy come into my place (about 4/5 years ago now) and ask if I knew anything about resistors, what they did, could I tell him the value of one he had, oh and where he could get them cheaply.
I gave him the info and a few months later he started to market them on eBay and the like, a few adverts in the car mags (so you can put "As seen in xyz") and he was selling a fair number of these.
The first lot were just a resistor with heat shrink tubing around it, then they were put into a small plastic "module" with two wires coming from it, which made it look quite good with custom packaging.
The address this guy gives in the ad is this area (only a mile or two from me) so I'm guessing, and this is only a guess, that it's the same guy but with a better designed unit so you don't have to solder it anymore.
I seem to recall (and this was a few years ago) that he said something about it tricking the ECU into thinking the choke was on and so compensating for it (I don't think he was too sure, I think he was just marketing an idea he'd pulled from somewhere).
So, if it is the same device, and it is the same guy, you will be buying a 2p resistor in a fancy box......Pet Rock anyone?