It goes by many nicknames: barf bag, sick sack, regurgitation receptacle. There’s one at every seat in the airplane, as ubiquitous as the tray tables and wedged between the in-flight magazines. You probably don’t even notice it, and if you do, you hope you won’t need it. But to a handful of people, the airsickness bag is a fascinating collectible.

Bruce Kelly has amassed a collection of 4,929 bags with hundreds of airlines represented. His collection also includes bags from ships and railways. You can browse photos of them on his site, on which he calls the bags “little icons of the sky.” While most are fairly generic, others sport bright designs, splashy advertisements, and tips for avoiding motion sickness. Collectors can arrange to swap their duplicate bags.

Kelly is not alone in his love for sick sacks. One site coined the term “bagophily” for the phenomenon. Collectors from around the world share their passion online, including these large collections:

Rune’s Barf Bag Collection: 1,289 bags
Air Sickness Bag Virtual Museum: 2,155 bags from multiple contributors
Bagland: 922 bags

If you still can’t bring yourself to view the bag as a potential collector’s item, you can always use it as an iPod movie watching case.—Kelsey Rexroat