Birds are incredibly smart, and challenging toys can provide hours of stimulation.  In nature, foraging for food and treats are part of daily life. Foraging Feeder™ is an incredibly strong plastic container.  It is actually made from materials used to manufacture bullet proof glass. That is why we say it is Bird Proof™!  Simply add nuts or other favorite treats to keep your pet challenged and stimulated.  The large is 4 inches.  Your birds will look forward to a fun mealtime when each meal becomes an adventure. Easy to hang with provided quick link.