Ocean Pro Snorkeling Inflatable Adjustable Vest with Pocket, Snorkel Vest, Snorkeling Vest, Swim Vest, Swimming Vest Nylon zipper front pocket for snorkeling extras Quick release adjustable waist and crotch straps Small is for the kids who are up to the age of 12, who weigh up to 88 pounds (40kg) Medium is for those that weigh 88 pounds (40kg) to 154 pounds (70kg) Large is for those that weight 154 pounds (70kg) to 200 pounds (90kg)