I guess I have had me head up me arse.
O-K here is the deal. Doc can tell you all what it is exactly, but I got to see it used by Doc in June on my visit to work for Doc at Profile Prospecting. I got to use it myself when Doc came out to San Diego for vacation.
The prototype functioned flawlessly and cut my carry load by about 8 pounds. As well, we both were able to go all day long 12+ hours - the prototype and me.
Ater that one day's experience, I told Doc to "just send me one when they are ready I don't care what they cost". I still don't know how much Doc wants for the thing and I don't care either - - - it is worth it.
My advice: save the money you might spend on a new coil or other prospecting gadget and get this thing. Your back will be so glad you did. You are going to find more gold because you can concentrate on those subtle changes in threshold instead of the nagging aching feeling caused from carrying all that extra poundage all day. This thing will help cut so much weight that you will be able to increase you water capacity and add additional safety items to your day pack without adding more weight than you are probably already used to schlepping around.
That's what I plan to do.
That and buy one of these as soon as they become available. Hey Doc - when is that exactly???