Feeder that can be fixed outside the cage where your bird can access food through guillotine door or that can be fixed inside the cage. Top is removable for easy and fast filliing. Food then falls to back of unit ad auto fills the station while hulls are dropped in to lower unit that is removable from outside. It is easy to clean and a great value. To be fixed outside the cage opening needs to be guillotine door at most 3.75" wide and at least 2.75" high.