As you sit comfortably (or uncomfortably) in your seat, do you ever pick up that duty-free catalog stuck in the seat pocket in front of you? Most probably don’t because let’s face it, when was the last time you bought duty-free while flying? It’s probably been years, maybe even decades.

By the time that trolly rolls through to the end of the aisle, the chance of a passenger buying at least one item is zilch. So why do airlines still offer duty-free on board when there are dozens of duty-free shops at airports?

For the most part, airlines still offer the service because it, surprisingly, brings in some big bucks for several airlines. According to GuestLogix, onboard duty-free sales brought in over $3 billion USD in 2015, with some airlines bringing in about $100 million to $200 million every year. The most popular purchases were skincare products, makeup and perfumes, followed by jewelry, watches, alcohol and cigarettes.

Korean Air offers Sky Shops, mini walk-in boutiques aboard 10 of its A380 aircraft, which offer cosmetics, perfumes, alcohol, fashion items and more. In order to make it fit, the airline has removed 13 seats on each plane in order to make space for these Sky Shops.

However, other airlines such as Delta and American already said goodbye to offering duty-free on board.

The airlines that still offer this in-flight service are trying to become more modern by removing the old-school catalogs, available in the back seat pocket. Instead, they are offering the ability to purchase duty-free via the entertainment system. Some airlines even give you the ability to buy items pre-flight and have them delivered to your seat once you’re flying or to your house. That way, you can skip the bagging and added luggage weight.