WASHINGTON (AP) — Four months after U.S. regulators tried to block imports of Elf Bar, the top-selling Chinese disposable e-cigarette remains widely available thanks to a simple but effective tactic: a name change. Stores in Washington D.C., Philadelphia, New York and other cities remain fully stocked with the brightly colored vapes, sold in fruity flavors like strawberry melon and claiming to contain 5,000 “puffs” per device. The Food and Drug Administration considers the products illegal.