It comprises at least a first layer (1) of a cold conducting material, characterized in that it comprises:- at least a second layer (2) on said first layer (1) and joined to it (1), defining some inner surfaces (3) between both layers configuring at least one housing (11), being both layers (1, 2) porous and absorbent, and- at least one cold conducting antifreeze gel (4), scattered in housing (11), on all the inner surfaces (3), said gel (4) having a freezing point below -12ºC, and a viscosity between 2000-90000 cPs at 21ºC, enough to pass through the pores of layers (1, 2) and to be removed from housing (11).
