Droll Yankees CPR Cardinal Perch Rings Fits all Droll Yankees new generation, classic and precious metals sunflower/mixed seed feeders, but is not compatible with Droll Yankees Ring Pull Classic feeders (A-6RP, TH-3RP) Converts straight perches to platform perches to attract a wider variety of birds. Birds can face the feeder directly rather than sideways, helping them to make the most of their peripheral vision Super strong polycarbonate design is easy to add or remove