①. 【See our size chart】: - Back length 30cm, chest circumference 54 - 64cm, life jacket weight about 0.174kg (Medium). - Back length 40cm, chest circumference 62 - 74cm, life jacket weight about 0.2kg (Large). - Back length 45cm, chest circumference 72 - 81cm, life jacket weight about 0.46kg (Extra Large). - Back length 50cm, chest circumference 82 - 92cm, life jacket weight about 0.32kg (XX Large). ②. 【Easy to put on and take off】: The dog life jacket has Velcro at the waist and neck, and there are buckles at both places. The buckle is adjustable, so you can easily help your dog put on the life jacket. Once you put it on, you can tighten or loosen it according to your dog's needs. ③. 【Unique Design】: The cute shark - shaped design with bright shark fins and other details increases the fun of swimming and allows you to clearly see where your dog is swimming. In addition, the safe buoyancy foam can help your dog swim without causing much fatigue. There is a handle on the top of the pet safety vest, allowing you to catch it with your hands or a hook, so you can save your dog in case of danger.