TUBEX XL is Driltech Mission's system for simultaneous drilling and casing in overburden and loose rock formations. The reamer bit, made larger to cut the hole wider, rotates by means of an internal driver, making it independent of the rotation direction. The pilot bit features a new head design, which improves flushing properties, and has the same diameter as the hole to be drilled. Engineered to withstand high working loads, the pilot bit shaft is thicker with an S-thread with broader contact surfaces. Shorter and lighter than its predecessors, TUBEX XL is intended to improve efficiency and allow higher drilling speeds. Driltech Mission.