What's the shim used on microwave circuit adjustment?

Is ther anyone can tell me what's the shim used on microwave circuit adjustment and whern can I buy it?

Thanks

They Are probably refering to a thin, flexible piece of metal. You can cut them into smaller pieces an solder them to your printed circuit board for adjusting the L's and the C's of your printed traces. They can also form walls to block radiation and decouple nearby circuits.

Thanks for your reply. Do you know where can I buy it?

check this website http://www.ejbco.com/