5 Size Basically For Cats and small to medium dogs Between 4-38 Pounds: Size2 (for young kitten and rabbits): 7.87- 9.05 4.92; Size3 (for cats and tiny dogs): 9.44-10.62 5.70; Size4 (for cats and small dogs):1 1.02-1 2.20 6.10; Size5(for small and medium dogs):1 2.59-1 4.17 7.08;Size6 (for medium dogs below 40 pounds):1 4.57-1 6.14 8.2 6.Please measure your pets neck before purchase. For the pets with bigger head, you can choose one size bigger. Breathable Mesh MaterialFar more breathable and comfortable mesh material than traditional plastic Elizabethan Collar. Lengthened Closure: Ajustable closure design enables dogs and cats cone easy to wear and adjust the tightness slightly. You can ajust it according to your pets sizes. Lightweight & SoftThese E-collars are light and soft, pets never feel unblance because of the extra burden. The cones seem do not exist. Specially Designed Edges: The edges are soft and comfortable, it will protect your pets necks, skin and hair. They can be used in many situations, like medical treatment, hair care, shower clean, after-care.