To combat counterfeiting, companies may have the various parts of an item manufactured in independent factories and then limit the supply of certain distinguishing parts to the factory that performs the final assembly to the exact number required for the number of items to be assembled (or as near to that number as is practicable) or may require the factory to account for every part used and to return any unused, faulty or damaged parts. To help distinguish the originals from the counterfeits, the copyright holder may also employ the use of serial numbers or holograms etc., which may be attached to the product in another factory.