Protect your birdfeeder from sparrows WITHOUT discouraging other desirable birds, Have more beautiful songbirds at your feeder and less wasted birdseed, Sparrow-Free Magic Halo is a patented wire hoop device with vertical extension wires that attaches easily to the top of a feeder, Studies have shown that certain bird species including house sparrows will not fly under these wires, University developed, 98 percent effective in studies, Any feeder: hanging tube stationary (pole mounted) or hopper, Improve your bird feeding program, With messy invasive house sparrows blue jays and common grackles out of the way desirable birds have: Better access and less competition at the feeder, More food since it is not wasted on pests, More time for predator scanning, Sparrow Free Magic Halo was developed after decades of research into risk aversion and foraging habits of birds, In university tests the Magic Halo alone (without lines) repelled 95 percent of house sparrows from bird feeding stations, The Halo also discouraged feeding by grackles and bluejays, The addition of the hanging lines increased the repellency to 98 percent, Developed by Dr, R, J, Johnson a professor in Wildlife Biology and Extension Wildlife Specialist in the School of Natural Resources at the University of Nebraska at Lincoln, SKU: BRDX024