What type of tool consists of two flat plates and is used for straightening hair?

The tool designed specifically for straightening hair, consisting of two flat plates, is the flat iron. Flat irons work by applying heat to the hair within the plates, effectively smoothing the hair strands and eliminating curls or waves. This method can create sleek, straight finishes and is well-known for its efficiency in achieving a polished look.

While curling wands and crimpers are used for creating styles that add texture or waves, they do not serve the primary function of straightening hair. A straightening brush, though it may assist in achieving straight hair by combing through heated bristles, does not have the same flat plate design as a flat iron and typically does not provide the same level of straightening power as the latter. Thus, the flat iron is the correct answer for its specific design and intended use in hair straightening.