Shake Shack just launched a Chick-fil-A killer - and it looks amazing

Shake Shack has launched a chicken sandwich.

The ChickenShack is a "crispy all-natural and antibiotic-free chicken breast with lettuce, pickles and buttermilk herb mayo," according to the company.

The sandwich will be available exclusively at Shake Shack's Brooklyn locations for a limited time.

It sounds like the chain is testing the sandwich for a larger rollout.

By making the ChickenShack a permanent menu item, Shake Shack would be taking direct aim at Chick-fil-A, the leader in the fast-fast food chicken market. The popular Atlanta-based chain surpassed KFC last year to become the No. 1 chicken chain in the US.

The menus at Shake Shack and Chick-fil-A are already pretty similar. Both feature sandwiches, french fries and milkshakes. But the only menu item containing chicken currently at Shake Shack is the chicken dog, which is a hot dog made with chicken, apple and sage sausage.

Shake Shack wouldn't be the first chain to go after Chick-fil-A's market.

Taco Bell parent company Yum! Brands has also been testing a chicken sandwich chain, called Super Chix.

Like Chick-fil-A, Super Chix sells fried chicken sandwiches, chicken strips, frozen custard, and french fries.

According to research firm NPD Group, chicken meals rose 3% to $5.4 billion for the year ending in March at fast-food restaurants, CNBC noted.