Avoid issues while shipping to US


I need to ship to US but I am completely new to shipments outside Europe. Do I need to declare something on the package shipping label in order to avoid problems with the customs?

I am saying this because, for example, OSHPark (which send bare PCBs from US) is declaring what type of stuff is in the envelope and its price. What happens if I ship an envelope with just the sender/recipient address using a normal public postal service? There is a particular form to insert other data like the good type and its value, if needed? Can I do something to speed up the shipment to US or other non EU locations?

Thank you!

A bit late response, but still “good to know” : For shipping outside an EU-country a CN22 or CN23 form (actualy a label) is required. This form is available at postal offices. This form contains the following info :

May be opened officially
o Gift
o Commercial sample
o Documents
o Other


Total weigth : … gram
Total value : … EUR

Date : …
Signature : …

I ship multiple times outside the EU and had several times to pay a visit to the postal office for this form, before able to ship an item. After a while, I created an identical CN22 label for my Dymo labelprinter. Now I print out a CN22 label, together with an addresslabel, whenever I need to ship an item. Never got any problems with this. I shared this CN22-label with the Dymo-company (and should be available for download, if I’m correct).