Product piracy costs companies around the world billions every year. Firms invest a lot of time and money in the development of their products - which pirates can then copy cheaply and easily.   Made in Germany accompanies customs officials at the "Ambiente" trade fair in Frankfurt. Investigators focus on searching for counterfeit products which they then withdraw from circulation. We listen in as manufacturers report on the damage they incur as a result of piracy. Report by Dan Hirschfeld