  Heat sink. 
Now this is a nice hunk of copper, the base a good 1/4" thick with lots of copper fins coming up from it.  Normally there is a fan mounted directly above the fins blowing air through them, but I've removed it so you can see the copper better.  The smooth bottom of the heat sink is pressed onto a large chip with some heat-conductive gel between them: This one is intended for cooling Intel CPUs. 
Source: Computer Store 
Contributor: Theodore Gray 
Acquired: 19 June, 2007 
Text Updated: 20 June, 2007 
Price: $35 
Size: 4" 
Purity: >99%
 |  
  |  
 |  
  |