What do you write on the customs form?

I am going to send some packages overseas and was wondering what to write on the customs form? Should I write coins and their face value, or something else? Do they open the packages to check what is inside and to make sure the label matches up?

Quote: "Hello There"​I am going to send some packages overseas and was wondering what to write on the customs form? Should I write coins and their face value, or something else? Do they open the packages to check what is inside and to make sure the label matches up?

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Write "Hobby Supplies' and the Value 10$;
That is what I always did.

I wrote Numismatics on the customs form and a value of $10.00 on a package to Bosnia and Herzegovina and had no problem.

"Hobby supplies" every single time. Value between $10 and $20, never more.

Great, thanks for the replies.