Size: M : Bust: 43-63 cm, neck circumference: 40-48 cm Please choose a suitable size : the life jacket is suitable for small dogs, medium dogs and large dogs. Please measure your dog's chest and neck circumference, especially the chest circumference. If the measurement is close to the maximum, please select the next larger size for a more comfortable fit on your dog. EXTRA DURABLE MATERIAL AND EXCELLENT WORKMAN : The life jacket is made of ripstop buoyancy pearl cotton as the main material. It can provide sufficient buoyancy in the water and does not restrict your dog's movements on dry land. It has an advanced breathable mesh underbelly for proper drainage and drying. Safe and reliable : Sturdy and more comfortable Velcro fastening system around the belly and neck to stay securely attached. Bright safety colors and reflective strip of reflections can improve visibility. You are able to quickly identify your dog in and out of the water. CONVENIENCE AND ADAPTABILITY : Adjustable