These Insect Inn Ultra replacement cartridges come in a pack of 4. The disposable design ensures that your restaurant will remain clean. These Insect Inn Ultra replacement cartridges have a 60-day lifespan that have the ability to capture over 2000 flies. The sticky surface ensures that pieces of the bugs will stay in one area and will not scatter. These Insect Inn ultra replacement cartridges replenish the scent that attracts flies to the unit.