Intel's new packaging for their latest Pentium III processors. The processor die is attached to a fiberglass PCB and surrounded with a special glue. The heat sink is affixed in such a way that it touches the die directly. The advantage: Better heat dissapation and less expensive design. The disadvantage: Much more fragile than before. One tiny mishap when applying the heat sink and you can crack the die, destroying the processor (and your day) in the process. Be careful.