The Type B-3 pneumatic life vest was developed by the Equipment Branch in an effort to enhance reliability of the personal flotation devices for military aircrew. It was standardized well before WWII, i.e. on January 8, 1936, and continued to see service until the end of the conflict. Its construction comprised an outer shell of yellow cotton fabric with two separate adjoining rubber cells made of latex, resulting in a sturdy device providing buoyancy in the ring around the neck as well as to the chest area. By pulling down on cords attached to two small discharge levers the wearer activated the automatic inflation system. Two small CO2 cylinders, one per bladder, were located at the bottom of the vest. Additional mouth inflation tubes were provided in case of leaks or failure of the CO2 system. All these features were to be checked regularly by the wearer in order to guarantee safe operation. Fortunately the B-3 was very reliable, as many aircrew reportedly were somewhat sluggish in performing those checks.