Atlanta-based Delta Air Lines is making permanent a guarantee that its passengers’ checked bags will arrive at the carousel within 20 minutes.

The guarantee only applies to Delta's U.S. domestic flights flown by members of the SkyMiles frequent flier program. But it's not a money-back guarantee for checked baggage fees — instead, Delta says if your bags arrive more than 20 minutes after the flight arrives, you can submit a request form on Delta's website for 2,500 frequent flier miles.

The small print notes that Delta “reserves the right to suspend this baggage service guarantee at any time” if there is an airport baggage system malfunction, severe weather or other conditions outside of Delta’s control that affect baggage handling.

The move is part of the company’s broader effort to focus on reliability, which Delta says “shows customers that we value their time.” It makes permanent the carrier’s limited-time offer that started in February. Alaska Airlines, which Delta is going up against in Seattle, has offered a baggage guarantee since 2010.