Which device is used for anchoring a lag screw into concrete, brick, or block?

The correct choice for anchoring a lag screw into materials like concrete, brick, or block is the expansion shield. This device is specifically designed to provide a secure grip within solid materials by expanding against the sides of a drilled hole when the lag screw is inserted. As the screw is tightened, the expansion shield expands, creating friction and holding the screw firmly in place. This anchoring method is essential for ensuring structural stability in various applications where traditional screws would fail to hold due to the density and hardness of the materials involved.

The other options do not serve this specific purpose: an ear tagger is used for tagging livestock, an electrical multimeter is for measuring electrical parameters, and a duplex receptacle is an electrical outlet. Therefore, the expansion shield is the unique tool designed for the particular task of anchoring lag screws in tough building materials.