The 17 inch Thistle/Nyjer Seed Feeder is made with UV protected stay-clear break polycarbonate plastic. The wider 6-sided tube allows easier filling, 6 feeding ports (instead of 4), and viewing for up to 50% more birds! Feeding holes above and below the perches birds can feed right-sight up and upside down! Threaded base accepts Natures Way Bird Products seed tray.