Sony Playstation 3 COPPER SHIMS. These shims are used between the CPU/GPU and heatsinks to provide better cooling for your PS3. This listing contains: 2 Copper shims that are are 42MM X 42MM and are 1.2MM thick and a 3.5g tube of Arctic Silver 5. Shims are 100% copper, cut and polished. Copper will tarnish when it comes into contact with air. This doesn't harm or alter your PS3 from working. You can buff your copper with copper cleaner or Brasso before installing. Totally up to you as it's only for looks. There are plenty of youtube videos out there that will show you how to open a PS3, perform a reflow, etc. When used in conjunction with a reflow and new thermal paste, the shims will greatly improve the life of your system!