a thin walled multi - well plate for pcr use comprising : a deck and skirt portion said deck and skirt portion having an outer surface and an inner surface ; a plurality of wells for holding chemical reactants , each well comprising a well wall having an inner surface and an outer surface ; wherein the deck and skirt portion and the plurality of wells are of integral construction and formed from the same plastics material , and wherein the deck and skirt portion has a mean thickness from 1 . 5 mm ± 10 % to 3 mm ± 10 %.