The documents relate to the marketing and sales practices of the company. The regulator is trying to understand why different electronic cigarette products, especially Juul products, are so appealing to teens. Juul currently commands about 72% of the electronic cigarette market in the U.S. Kevin Burns, the CEO of Juul Labs, revealed that they are cooperating fully with the regulator in order to be part of the solution to what the FDA calls an epidemic of teen vaping. It is not yet clear which other e-cigarette makers will be the subject of similar seizures.