WSJ's Jennifer Maloney details how a product called Puff Bar has become the top-selling vape among kids. But thanks to a loophole in the FDA's rule, sweet, fruity flavors are still around.

FILE - In this Jan. 31, 2020 file photo a woman holds a Puff Bar flavored disposable vape device in New York. U.S. health officials are cracking down on the brand of fruity disposable e-cigarettes ...

The transition isn’t without its challenges. Lawmakers move to enforce sweeping ban on popular convenience store product: 'I ...