Thirroul appears to be the target of criminals armed with ATM skimming devices after a card reader was found at the Commonwealth Bank on Saturday - the second incident in the suburb in the past two months.The device, which uses mobile phone technology to skim details from customers' bank cards, was found attached to the ATM on Lawrence Hargrave Dr about 2.40pm.Detective Senior Sergeant Brad Ainsworth said the bank's manager was alerted to the device after the machine swallowed several users' cards. He immediately contacted police and secured the machine.A skimming device was found in June on another ATM in Thirroul, as well as an ATM at the University of Wollongong's UniCentre food court.In most ATM skimming incidents, the criminals attach two devices to the machine - one that covers the card slot and can record card details, and another device that is fitted with a camera to record PINs.Both devices are cannily designed and difficult to detect as they almost seamlessly blend in with the colours, styles and materials of the ATM.The information is recorded by mobile phone technology and transmitted wirelessly to the criminal.Snr Sgt Ainsworth warned ATM users to be vigilant and to inspect every machine they use."Report any difficulties to the bank immediately," he said."Always cover the key pad with your hand when entering PINs and inspect the plastic facade that surrounds the card and receipt slot."Just get it and grab hold of it and if it falls off, well, you know it's bad."