The 16 oz. nectar capacity holds just enough to make sure there is always fresh, clean nectar for your tiny hummingbirds. The wide mouth opening on the glass feeder bottle makes filling mess-free and cleaning simple. The built in bee guards on the 4 feeding ports protect the nectar supply and your hummingbirds from bees. The built in ant moat on the lid keeps ants away. Simply fill with water! The base of this feeder easily comes apart to clean. To prevent mold buildup, remember to clean your feeder twice a week with a mild soap and water solution.