A counterfeit is something marked with a brand name which is not genuinely produced by that company or designer. Counterfeit designer jeans, designer shoes or a handbag may be perfectly serviceable items. The same cannot be said of counterfeit flash.
Unlike counterfeiters of designer goods the counterfeiters of flash memory do not just defraud people out of money and make a dent in the designer’s and manufacturer’s profits. They cause people data loss by programming the flash to report itself as a higher capacity than it really is.
Common targets for counterfeiters of flash include Sony Sandisk and Kingston. If you buy a counterfeit drive you should contact the police and the manufacturer as well as the parties involved in the sale. If you purchased the drive on ebay the parties involved include the seller, Ebay, Paypal and (if you paid with your credit card) your credit card company.