6 inch down the hole drill dth hammer bits Down The Hole Bit, usually called DTH bit, is used with DTH hammers for drilling holes through a wide range of rocks types. In conjunction with DTH hammers, DTH bits are designed with a splined drive for rotating the bit in the ground. Drill bits are available in different sizes and different styles so they can drill a wide range of hole sizes. Our variety of DTH bits are manufactured using high quality materials to provide you with a fine balance between penetration capability and bit life. We offer a comprehensive range of standard and made to order drill bits on an extensive selection of shanks with a wide variety of head designs to suit every project.