I have a dozen old 40mm square Peltier cooling/heating units (see photo) from 12-volt heater/coolers, and no additional specifications. They are yours with which to experiment for $4 each (with free shipping), $26 for all twelve (also free shipping), or any other amount
n for $4n^(3/4) to the nearest quarter-dollar, with free shipping and a moneyback guarantee, and a one-dollar penalty for mis-calculating the cost.