This Auction for total of 10 copper shims pads 20x20 mm  they come in different thickness as following:

2 of Copper shim 20x20x0.3 mm
2 of Copper shim 20x20x0.5 mm
4 of Copper shim 20x20x1 mm
2 of Copper shim 20x20x1.2 mm


Specification:

 Picture is been captured from exact similar item you will receive !

 
The copper piece is high-purity copper.
Thermal conductivity up to 401w/mk. (The ordinary copper thermal conductivity only 20-30w/mk )