My Preview Hendrix cage came with bowls you slide in and close the door. However, those bowls did not have a perch. Young birds do not always have good balance to eat from cups without perches. So these Living World Seed Cups come in handy. The large size was enough to cover the open hole of the cage where my old feeder cups went. I use this size for my cockatiel. They wash up easily and last a long time..