ISO 1722:1974

Rock drilling — Extension drill-steel equipment for percussive long-hole drilling — Reverse-buttress-threaded equipments 1 1/2 to 2 1/2 in (38 to 64 mm)

Specifies the basic dimensions for equipment. Gives a list of components; tabulates together with figures: size of drill-steel in bar form; lengths of extension rods; coupling sleeves; bit diameters (four-wing bits); reverse-buttress threads; hollow hexagonal bars for extension rods.