The kit of veterinary (animal) anesthesia masks includes: Animal Type Size Type Small mouse Size 0 Small Feline Size 1 Feline Size 2 Small canine Size 3 Medium canine Size 4 Large canine Size 5 Diaphragm diameters: Animal Type Size Small mouse int = 2.1cm (0.78") ext = 4.7cm (1.85") Small Feline int = 3.2cm (1.26") ext = 5.5cm (2.17") Feline int = 4cm (1.57") ext = 6.5cm (2.56") Small canine int = 3.5cm (1.37") ext = 9.0cm (3.54") Medium canine int = 4.2cm (1.65") ext = 11.2cm (4.41") Large canine int = 7.3cm (2.87") ext = 13.7cm (5.39") Material Polycarbonate and silicone rubber