1. 【Check Our Size Chart】: Back length 30 cm, chest circumference 54 - 64 cm, life jacket weight approximately 0.174 kg (medium size). Back length 40 cm, chest circumference 62 - 74 cm, life jacket weight approximately 0.2 kg (large size). Back length 45 cm, chest circumference 72 - 81 cm, life jacket weight approximately 0.46 kg (extra - large size). Back length 50 cm, chest circumference 82 - 92 cm, life jacket weight approximately 0.32 kg (XX - large size). 2. 【Easy to Put On and Take Off】: The dog life jacket has Velcro on both the waist and the neck, and there are buckles at both places. The buckles are adjustable, so you can easily help your dog put on the life jacket. After putting it on, you can tighten or loosen it according to your dog's needs. 3. 【Unique Design】: It features a cute shark - shaped design, with eye - catching details such as a shark fin, which adds fun to swimming and allows you to clearly see the direction in which your beloved dog is swimming. In addition, our safe buoyant foam can help your beloved dog swim easily without causing too much fatigue. There is a handle on the top of the pet safety vest, which makes it convenient for you to grab it with your hand or a hook to protect your beloved dog in dangerous situations.