Pro Select Metal ID Card Holder for Cage, 3-Inch Metal ID Card Holders make it easy to display important information on animal cages Heavy-stock aluminum is durable, and the third hook prevents pets from removing the holder from the crate or wire kennel doors Perfect for clinics, animal hospitals, grooming shops, shelters, and rescues Designed for use with ProSelect cages and crates 4" x 6" size is also available