(ABC 6 News) – Rochester law enforcement urges everyone to be aware of credit card skimmers after one was spotted in Rochester earlier this week.

Skimmers are used to swipe credit card information from consumers as they check out.

Though subtle, skimmers usually reveal minor differences in the length of the card reader.

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Lieutenant Malinda Hanson with the Olmsted County Sheriff’s Office notes a couple differences that give it away. “There might be a protrusion on where you put your card in or they might be thicker where you run your card.”

Skimmers are most likely added where there are no cameras nearby, such as at outside ATMs or in older businesses.

This happened to Mohamed Abdi while he was on vacation in New York. “You could see a couple scratches here and there. I just assumed the machine was old. I assumed nothing was wrong with it. It was my first time traveling.”

In addition to noticing the differences, Hanson also wants people to check if there is anyone just standing close to the credit or debit card machines.

Scammers must stand close to their skimmers so they can receive the information via Bluetooth. It also allows them to watch people type in pins.