Fruits and vegetables give off ethylene gas. Exposure to this gas speeds up the ripening process in neighboring produce in a container or Crisper, causing it to spoil faster. GreenSaver's all-natural, non-toxic activated carbon filters are filled with nooks and crannies that trap and absorb ethylene gas, slowing down spoilage and keeping fruits and vegetables fresh longer. These filters are for use with OXO Good Grips GreenSaver Produce Keepers or Crisper Inserts. Carbon filters last 90 days. To sign up for reminders when it's time to replace your filter, or to learn more about the OXO GreenSaver line, visit greensaver{dot}oxo{dot}com