(CNN) - Walmart is launching a new tool to help shoppers make sure they get the best price.
It's called "Savings Catcher" and is available in select cities. All you have to do is enter your receipt number online. Then Walmart checks advertised prices in your area. If the "Savings Catcher" finds a price lower than what you paid, Walmart will make up for it. They say they'll give you the difference on an e-gift card.