American mountaineer and equipment manufacturer, Yvon Chouinard, first produced his lightweight Hexentric chock/nuts in 1974 which he made lighter by drilling holes in them. Scottish mountaineer and prolific gear modifier, Bill Skidmore, got hold of some Chouinard Hexentrics sometime after 1974 and made them lighter still by drilling even more holes in them!
Bill passed away in 2015 and his partner, Mary Henery, kindly gave us a whole pile of modified gear including these Hexentrics – thanks Mary.