... for "down-the-hole". The down-the-hole drilling is used to produce large-diameter holes in rocks, usually in the ... upwards instead of downwards.DTH Drill RodsDTH drill rods are used for connecting DTH hammer and DTH button bits; they are ... , basically, smaller DTH hammers need smaller DTH drill tubes, vice versa. Usually we are offering 76mm, 89mm, 102, 114mm, etc. Our ...