Children's Life Jackets are sized according to weight range and chest size. Weigh your child and measure their chest under the arms before you go to pick one out. Be sure it fits snugly. To test it, lift the child up by the shoulders of the life jacket to make sure it will not slip over the chin or ears.
It can be difficult for a child to float in a face up position because of the distribution of the body weight and a child's tendency to struggle or attempt to climb out of the water. If one does not work well, try another style. Straps around the legs are particularly important on children's life jackets, as they keep the device in place. They should be used whenever the life jacket is on. If the child does not swim, a Type II device is recommended to help keep the child face up in the water. Even though a life jacket is designed to keep a child afloat, it does not substitute for supervision. Never leave a child unattended.