They take the UPC code number that these sites list on thier pages, and then find a site that has an encoder for barcodes. After they imput the numbers into the encoder, the page presents them with what the scannable barcode that the game has is. They then take sheets of these printed out barcodes and use them at the price checkers that store have around... this way, if they know about a clearence at a specific store, they can find out if the game they want are on clearence before they bother to go find someone to open the can and scan it for them.