In U.K. in the early 1960s John Brailsford designed the first MOAC style nuts. Ellis Brigham Sporting Goods began producing and selling the nuts naming them MOAC for “Mountain Activities”. Originally the nut was made in one size with the idea that climbers could modify the taper and width as needed. In the early 1970s Ellis Brigham began offering sizes #1 through #4 both wired and slung.
MOAC nuts are simple and effective in a surprising range of placements. I have been carrying one on my rack for several years now and when it slots into a perfect placement it is a thing of beauty.