If your wool dryer balls shipment is arriving via Air or Sea Cargo. You need to release it from customs. However, this does not apply if you have ordered your shipment via Courier express (door delivery).
If you want to clear U.S. customs with cargo, you’ll need to submit documentation like CBP Form 3461 and CBP Form 7501. If your cargo is coming in on an ocean carrier, you will also need to submit an ISF Filing. A customs broker is not required for importing, but they can make the process easier even for experienced importers.
Search for a Customs broker (by Location) – US Customs and Border Protection Official webpage