[1] The very smallest nuts are known as micronuts and may be made of brass or other metal, and typically have their wires soldered into them, instead of looped through drilled holes.
They are mostly used in aid climbing, and their value as protection, arresting a climber's fall, is marginal because of both their low breaking strength and their tiny surface area (the HB 0 measures about 4 x 7 x 2.5 mm) in contact with the rock, though this can be offset if several are placed at a time.
In addition to using pitons, they picked up machine nuts from the side of railway tracks, climbed with them in their pockets, and used them as artificial chocks.
Nuts or chockstones are named after natural stones occasionally found wedged into cracks.
With Tom Frost, Chouinard invented a larger, six-sided nut called a Hexentric or hex.