Adopted of stainless steel material, this protective ring is specially designed for preventing the birds biting this nest or breeding box, thus causing some damage. With this proper ring, it will provide better rationalized protection and prolong the service life of breeding box. Features -Color:Silver -Material:Stainless steel -Size(1):15.00X15.00X2.00cm/5.89X5.89X0.79in -Size(2):12.00X12.00X1.50cm/4.72X4.72X0.59in -Size(3):11.50X11.50X1.50cm/4.52X4.52X0.59in -Size(4):10.30X10.30X1.50cm/4.05X4.05X0.59in -Size(5):9.50X9.50X1.00cm/3.73X3.73X0.39in - Versatile use: can be used as a bird cage, bird nest, breeding box, etc., meet your using needs. - Easy to assemble: simple and easy to assemble, no tools required, save your time and your efforts. - Practical design: with a smooth surface hole for birds to enter and exit, convenient and practical. - Anti-bite material: with an anti-bite ring, this breeding box guard can effectively prevent birds from biting. - Specially designed to prevent your parrot from damaging this nest easily with bird house guards. Packing list5 x bird breeding box guard