A “Peltier” is a solid state Thermoelectric Module.  When powered, it acts like a solid state heat pump (thanks to the Peltier effect) that transfers heat from one side of the device to the other.  Computer enthusiasts sometimes place the wafer like device on top of the processor of their computer with the hot side facing a water block to enhance the cooling of the processor.  Thermoelectric Modules ratings include max temperature difference and max cooling capacity, among others.