The tool consists of at least two concentric pipes which are forming two hydraulic channels - one for pumping down a high-pressure working agent (water) and second for delivering pregnant slurry back to the surface. A BHM tool usually has (down-up): an eductor (waterjet pump) section, a hydromonitor section, an extension section, and a hub connecting it all to a drill pipe string. This string extends the tool up to the surface. Above the surface, the tool has a swivel allowing its suspension and rotation in a hole, and also connections to the working agent supply (pump station) and a slurry collector. A drill rig is normally required to operate a BHM tool.