We've all heard the warnings about credit card skimmers.

Those are devices used to collect your credit or debit card information when you swipe at an ATM or at gas stations.

But there's another device to be on the lookout for -- credit card shimmers.

So what are they?

A shimmer is a paper-thin, card-shaped device that's wedged inside of the card slot of an A-T-M or gas pump terminal. It has a microchip and flash storage that intercepts data from your credit or debit card. That information is used to create a phony magnetic strip version of your card that can then be used by criminals on card readers that haven't been updated with E-M-V chip technology.

And they're hard to detect since they're hidden inside of the card reader.

So if you can't see them, how do you stop yourself from falling victim?

The Better Business Bureau suggests using the tap-and-go credit card feature instead of swiping your card -- whenever possible.

Another option is mobile services such as Apple Pay or Samsung Pay.

Use ATMs inside of banks, or just withdraw cash the "old-fashioned way" from a teller.

Finally, if you feel resistance when you insert your card, take it out and immediately stop the transaction.

The BBB suggests that you always keep a close eye on your credit card statements and debit accounts and report anything suspicious.

And if something seems to be off during a purchase or if you're withdrawing cash from an ATM, be sure to make the store or bank aware.