To protect the buoyancy chamber and activation system, a highly resistant outer casing has been developed. This casing must be tightly closed around the entire perimeter but must open immediately as soon as the inflation system is activated. There are two types of closure – with double Velcro edging or with a special zip. The zip has two ‘break’ points (Burst System or Quick Release) – one at the beginning of the chain teeth, folded inside the case, the second near the activator. At these two strategic points, the teeth of the zip are visually missing and it is precisely these missing teeth that allow for the correct and immediate opening of the flotation system.