Please note this is in Asian sizing, Asian size is smaller than western size e.g. UK, US, AU, please check the measurements carefully before making a purchase. Please allow 2-4cm error due to the manual measurement and different measurement methods. If you are not sure which size to buy, please provide weight, we will recommend a suitable size. XS: back length 18cm (7.1 inches), chest 26cm (10.2 inches), fits weight 1kg; S: back length 24cm (9.4 inches), chest 34cm (13.4 inches), fits weight 1-2kg; M: back length 29cm (11.4 inches), chest 38cm (14.9 inches), fits weight 2-3kg; L: back length 34cm (13.4 inches), chest 44cm (17.3 inches), fits weight 4-5kg; XL: back length 38cm (14.9 inches), chest 48cm (18.9 inches), fits weight 5-8kg; Please allow slight color difference due to the monitor