Groups, gangs and sometimes individuals are engaged in illegally obtaining merchandise through both theft and fraud in substantial quantities as part of a criminal enterprise. These crime rings generally consist of "boosters" - who methodically steal merchandise from retail stores - and fence operators who convert the product to cash or drugs as part of the criminal enterprise. Sophisticated criminals have even found ways to switch UPC bar codes on merchandise, so they ring up differently at checkout, commonly called “ticket switching.” Others use stolen or cloned credit cards to obtain merchandise or produce fictitious receipts to return products back to retail stores.