The heatsink base is a fairly thick piece of aluminium, shaped so that it lies flat on the processor core and the 4 memory chips that surround it. Glued or welded to the base are several pieces of what appear to be thin steel, whose purpose being to increase the total surface area of the heatsink. Unlike many heatsink designs, the fan is not located above the core - instead cool air is drawn in and directed across the pieces of steel and sink base via the plastic shield.