These unique electronic components can generate a temperature differential when powered. That is to say, apply 5V to the red (positive) and black (negative) wires and one side will get cold while the other side gets hot. For best results, you’ll need to wick away that heat (otherwise the cold side will slowly get warmer). A fan and/or heatsink is ideal.
This module is a 5V module, and is rated for 5W max (5V/1A) but when we plugged them in they seemed to draw more like 1.5A so we suggest our 5V/2A power adapter for use.