23 of fig4 has been omitted although it could be retained if needs be whilst the seal 24 is deliberately exposed to ambient air flow in this embodiment it will be noted that a vapour barrier is formed at the outermost edge of the seal profile to prevent moisture bypassing the seal 24 and so to discourage the formation of condensation or ice under or around the seal 24 as the perspective view of the inverted lid 1 in fig6 shows the rectangular seal 24 is accommodated in an outboard position by virtue of bulbous curved corners 25 of the lid 1 a further alteration is evident in fig6 and particularly in the sectional view of fig5 namely an insulating flange or skirt 26 inboard of the seal 24 this helps to shield the seal 24 from low temperatures within the drawer 2 the principle is based upon a temperature gradient from say u2212 20 celsius within the drawer 2 immediately inboard of the flange or skirt 26 through to ambient temperature immediately outboard of the seal 24 the position thickness and conductivity of the various rim interface elements arrayed across that temperature gradient will determine the outward extent of a sub zero region.