Shaft length can be varied by adding or removing sections. Probes can be used to examine the soil to a depth of 2 meters. A pedal that is attached to the shaft is available to allow the operator to apply body weight. Some workers carry rubber or plastic mallets to drive the tube into the soil. A pair of pipe wrenches is needed to add and remove lengths of shaft.
Probes work well in moist, medium textured soils that are free of gravel, stones, and dense layers.
Under these conditions, the soil can be examined faster than with an auger. Probes are very difficult to use in dry, dense, or poorly graded soil, and in soil containing gravel or stones. Probes disturb the soil less than augers, but they retrieve less soil for examination. Probes are light and easily carried, and they pull from the hole more easily than screw augers. Often a special punch or dowel must be used to clear the tube.