Combined with the size L i bought it fits my cacatau. Size M on it's one it is then suitebla for maybe a canary. On the photograph you see my little finger where the neck of the bird should be. Fabric is also not right for use with birds.
Size L suitable for a parrot? No more suitable for a little parakeet. Fabric also not good to resist a parrot or any other bird for that matter. I bought a Size M also and combined with eachother it fits my cacatau.