Have you ever wished your hummingbird feeder could expand as more hummers visited in August to October. Now it can. Introducing switchable seasonal sizing. This system allows you to cater to your hummer population by offering several sizes of replacement bottles, all that fit perfect on your Dr. JB's clean feeder making the best hummingbird feeder on the market even better. Features wide olive jar size mouth for easy bottle cleaning. Easy to clean base is dishwasher safe. Doesn't leak, making it bee and wasp-free. Allows you to cater to increased nectar consumption during migration season. No more going home at lunch just to fill your feeders. These jars are unbreakable, stronger than glass while offering easy clean wide opening.