The Atlanta-based company launched Frosted Lemonade in 2015 and also has a Frosted Coffee.
"We are delighted to launch another seasonal, frosted treat this spring,” Leslie Neslage, menu lead for the menu and packaging team at Chick-fil-A, said in a statement. “Frosted Key Lime is both tart and sweet and will be a delicious, lower calorie treat that all customers can enjoy throughout the day.”
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The treat was tested in Austin restaurants last fall and "positive customer feedback confirmed the decision to launch the treat nationwide," Chick-fil-A said.
The drink combines the chain's vanilla IceDream, lemonade or diet lemonade and "a natural, sugar-free lime flavoring made from a blend of key limes, kaffir limes and Persian limes," it added.
A 16-ounce Frosted Key Lime starts at $3.25 and with diet lemonade has 280 calories and the regular has 350 calories.
Select locations have another seasonal item available through April 20 – a fish sandwich. It's not available every day and is not widely available nationwide.
It's one of the many fish specials that restaurants have leading up to Easter for lent.