The device pictured in Krebs' post even includes a motion-activated pinhole camera aimed at the ATM's control pad to record a victim's PIN.
I strongly suggest checking out Krebs' full blog post for additional pictures. Being able to recognize a skimmer could save your company thousands of dollars and a world of trouble.
A skilled thief can build an ATM skimmer out of parts scavenged from MP3 players and other easily available components. A well-built skimmer will fit smoothly -- but usually not seamlessly -- over the mouth of the machine's card reader.
Thieves realize that a reader gives them an effective, and relatively safe, way to gather card data and PINs from their victims. When the scam works, they can retrieve the device at their convenience; when it doesn't, they simply spend a few dollars to build another skimmer and try again elsewhere.
Krebs offers some sound, common-sense advice on how to avoid this scam. "Practice basic ATM street smarts and you should have little to fear from these skimmers: If you see something that doesnt look right  such as a odd protrusion or off-color component on an ATM  consider going to another machine. Also, stay away from ATMs that are not located in publicly visible and well-lit areas."
Needless to say, ATMs attached to physical bank branches -- especially during regular business hours -- are probably less vulnerable to skimmer attacks. The next time you visit an ATM during off hours or at a stand-alone location (including drive-up ATMs), don't let convenience outweigh the need to protect your small business against these increasingly common attacks.