Guaranteed to trim a bird?s nails and beak naturally. Variable size promotes healthier feet and leg muscles. Bird chooses the thickness and shape for the most comfortable fit. Indestructible to the strongest beak. The textured, non-slip surface is safe for bird?s feet. Veterinarian tested and approved. Available in 11 different sizes ranging from canaries and finches all the way up to the largest macaws and cockatoos.