These Calcium Perches are made from calcium to help keep your bird's nails and beak trimmed. They are easily attached and removed by hand with the wing nut assembly for easy cleaning, maintenance and repositioning. Calcium is beneficial in preventing soft shells and promoting healthy feather and bone growth. Small - Finches, Canary, Parrotlet, Budgie Medium - Cockatiel, Conure, Quaker, Lorikeet Large - Galah, Eclectus, Amazons XLarge - Cockatoo, Eclectus, Macaws We recommend rotating these perches weekly, and they are best positioned at mid-cage height. Remember to combine with natural perches as well. Perches are sold individually; pictures are for reference only. For the right spot to hang a calcium perch and what else the cage needs, see Which Perches Should You Put in a Bird Cage?