This system allows you to cater to your Hummer population by offering several sizes of replacement bottles, all that fit perfectly on your Dr. JB's Clean Feeder- making the best Hummingbird feeder on the market even better! Switchable bottles allow you to cater to increased nectar consumption during migration season. No more going home at lunch just to fill your feeders! Features unbreakable wide-mouth bottles for easy cleaning and an easy-to-clean base. No leaking makes it Bee and Wasp free! Hand wash with warm soapy water and always follow up by rinsing parts with a mild bleach and water solution before re-filling with sugar and water.