Extra Small
for pets 0-9.9 kg, 76mm H x 86mm W x 111mm L 

Small
for pets 10-19.9 kg, 76mm H x 111mm W x 136mm LL

Medium
for pets 20- 34.9 kg, 76mm H x 121mm W x 196mm L

Large
for pets 35-49.9 kg, 96mm H x 121mm W x 196mm L

Extra Large
for pets 50+ kg, 96mm H x 136mm W x 226mm L