New York (CNN Business) McDonald's family of Big Mac sandwiches is growing with two new additions.

McDonald's MCD Beginning Thursday,is adding a Little Mac and a Double Big Mac to its menu, for a limited time. They are smaller and larger, respectively, versions of its flagship Big Mac hamburger.

McDonald's will serve a Little Mac (left) and a Double Big Mac (middle) beginning Wednesday.

The Little Mac is similar to a McDonald's single cheeseburger: It's a single patty with a dollop of Special Sauce. It costs $2.29.

The Double Big Mac, which costs $5.49, has four burger patties. It has 720 calories and 43 grams of fat.

By comparison, a regular-sized Big Mac, which has two patties, costs $3.99. It has 540 calories and 30 grams of fat.

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