Extra-strong SBS zipper with Velcro closure and top protection to prevent chafing on the neck and chin. Inside, it has 8 compartments, each with 3 pieces that provide buoyancy around the torso and can be removed as the child gains more confidence and ease in the water. The vest has a strap with a safety closure that can be placed between the legs to prevent the vest from slipping over the head if the user dives vertically into the water or simply floats in the water. This strap is protected with neoprene to prevent chafing between the legs. Protects from the sun's rays with its UPF 50+ protection factor. * Small : From 2 to 4 years approx., weight 11 to 19 kilos, chest circumference 55-64cm. * Medium: 4-6 years, 19-30 kg, chest circumference 64-70 cm. * Size S has 2 flotation elements at the height of both clavicles to regulate the flotation angle. * We recommend that you use your child's chest circumference as a guide to choosing the correct size. Age is a guide only. * EN13138-1:20