... and underground foundation work all over the world. 2) API and ISO certificate 3) we are a ... easiest to log. Usually 2-wings drag bit, 3-wings drag bit, 4-wings drag bit optional. ... & step as requested. Sizes: 3 3/4", 3.7/8", 4", 41/4", 55/8 ", 47/8", 6", ... 5/8", 5.7/8", 6.1/4", 6.3/4", 6.5/8" 7.3/8" 9 ... 2" etc as requested. Our standard type already exported to USA, Australia, and Japan etc. more than 30 ...