Google is testing out a price guarantee program for Google Flights that will pay you money if the price of a flight goes down after you booked it through the service. The feature is currently available as a “pilot program” in the US (get it?) for specific flights, according to a Monday blog post, but it could be a compelling reason to use Google’s tool the next time you’re searching for a flight.

When you’re using Google’s tool, some flights will have a little shield icon with a dollar sign. If you book that particular flight through Google Flights, the company says it’ll “monitor the price every day until departure.” If it drops, you’ll get the difference back.

Currently, its price guarantees are only for flights that depart from the US, and you can only get them if you have a US billing address and phone number. The company also says it’s “only available for flights for which we’re confident that the price won’t drop.”

There are a fair number of asterisks. A lengthy help document from Google explains that you can only get $500 back per calendar year and that you won’t get money back if the price difference is less than $5. You also get the refund through Google Pay, which you’ll have to set up within 90 days of receiving the notification that it’s available. Also, of course, you have to book your tickets through Google Flights.

The company says you should receive the difference within 48 hours from when you took off, assuming you already have Google Pay set up.

A price guarantee isn’t unique among travel sites; Priceline and Orbitz both promise partial refunds under certain circumstances, as do some individual airlines. But usually, they require you to go looking for a better price instead of continuously monitoring for one themselves. 

Google’s blog post also mentions another feature that the company rolled out: the ability to explore hotels in an area through a “swipeable story format,” which shows a slideshow of a hotel that you can swipe up on to be shown another hotel. Stories are coming to everything these days, and it seems like Google Maps is no exception.