<P> Drifting in open seas and international waters, as encountered on long sea voyages and by military forces, requires prolonged survival in water . Suitable life jackets are often attached to a vest with pockets and attachment points for distress signaling and survival aids, for example, a handheld two - way radio (walkie - talkie), emergency beacon (406 MHz frequency), signal mirror, sea marker dye, smoke or light signal flares, strobe light, first - aid supplies, concentrated nutritional items, water purification supplies, shark repellent, knife, and pistol . </P> <P> Accessories such as leg straps can be utilized to keep the inflated chambers in position for floating in a stable attitude, and splash or face shields constructed of clear see - through vinyl covers the head and face to prevent water from waves from inundating the face and entering the airway through the nose or mouth . </P> <P> Some formats of PFDs are designed for long term immersion in cold water in that they provide insulation as well as buoyancy . While a wetsuit of neoprene rubber or a diver's drysuit provides a degree of flotation, in most maritime countries they are not formally considered by regulatory agencies as approved lifesaving devices or as PFDs . </P> <P> It is possible for an incapacitated person in the water to float face - down while wearing only a wet suit or a dry suit since they are not designed to serve as lifesaving devices in the normal understanding of that term . </P>

What kind of foam is in life jackets