I picked up a '75 strat that had these in there. (along with the originals in the case). They appear to be very well made (slightly hot 8kB, 7.5kRWRM, 7.1kN). Absolutely killer tone. But I can find no info on the net. Someone put a good bit of time into these and I'll leave them be. This 75 is just about 8lbs and with a new nut and fret job it is an exceptional example from an inconsistent era.