Grain Probes for sampling large volumes of grain by hand. They consist of an inner "tube" within an outer "tube" both of which have slots. The inner "tube" is rotated closing slots when probe is inserted into a grain mass. Another rotation opens the slots so grain can flow into the "tube". A final rotation closes the slots and "traps" grain so that the probe containing the sample can be removed.
Photograph provided by Seedburo Equipment Company, Chicago, IL.