Abstract: A tool intended for use in conjunction with carrier machinery, primarily a rockbreaker, comprising two axially aligned elongated members, one of which may be introduced into the carrier machinery with one end and into a recess in the other (second) member with its other end. A third member surrounds the second member and is suspended by the carrier machinery. When the carrier machinery is in operation it impacts the engaging end of the first member, thereby impacting the second member, which may operate as a plunger for producing holes in the ground. The second member is driven into the ground in consequence of a series of short impacts of the carrier machinery on the first member. The second member is provided with means for engagement by the third member to enable the second member to be pulled out of the ground when the hole has the required depth.