... -138mm 2.Reliability quality 3.Simple structure and easy operation 4.Long service life Usage:Drill holes from 105mm to 152mm ... .Matched products:76mm drill rods with API 2 3/8"REG BOX bits with COP44.DHD340A,Mission40,QL40,SD4,XL4 ... , tunnel, bridge, construction and etc., but extremely exellent to use with casing tubes during casing drilling.Features: 1.high impact power ...