While the service doesn't seem to cover charging cases, its coverage includes wireless buds' batteries and the charging cables they shipped with. Plus, it buys subscribers priority access to Apple's customer service. Those interested can simply add AppleCare+ to their cart when they buy new headphones from Apple's online store. They also purchase it from a brick-and-mortar Apple Store or by calling (800) 275-2273 within 60 days upon getting a new pair -- it can't be purchased online by itself.
According to 9to5Mac, though, the service doesn't cover theft or loss coverage. That means those who've lost an earbud in the subway, which seems to be a growing issue for the New York Metropolitan Transport Authority, would still have to buy a replacement.