Just a few months ago in May, we reported that Cedar Rapids police had found a skimmer device on a Blair's Ferry Rd. gas station pump.

Yesterday, cops in central Iowa found three skimming devices at local pumps in the small town of Clive.

Experts say the machine tampering continues despite law enforcement's best effort to thwart criminals. But there are ways to protect yourself, and it starts with knowing what to look for.

You might be surprised and disturbed at how non-assuming a skimmer device can look. The device on the left in the photo below looks like a simple extension of a legit card reader. But you can see in the photo on the right, that "extension" doesn't belong there.

Skimmer photo courtesy of Royal Canadian Mounted Police (via FTC.gov)

You should also look for signs of tampering with the seals that would likely be broken if thieves has rigged a device into the pump's credit card door (see below).

Photo credit: National Association of Convenience Stores (NACS) and Conexxus/ FTC.gov

If you're still paying at the pump you may be think twice and simply begin paying inside the gas station to avoid the possibility of being fooled.

[source: FTC.gov WeAreIowa.com]