ingle-Door Folding Metal Dog Crates: Ideal for Puppies, Small Breed Dogs, Cats, Kittens, Rabbits and (Adult) Guinea Pigs, Jainsons single-door folding metal crate offers exceptional convenience. Use the metal crate for anything from potty training or house training to reinforcing house rules and boundaries-or simply as a safe, secure place for your pooch to rest and relax.