The Brewster Body Shield or Brewster Body Armor was the first effective body armor developed for the United States Army in World War I, designed by Dr. Guy Otis Brewster from Dover, New Jersey.During World War I, the United States developed several types of body armor, including the chrome nickel steel Brewster Body Shield, which consisted of a breastplate and a headpiece and could withstand .303 British bullets at 2,700 ft/s (820 m/s), but was clumsy and heavy at 40 lb (18 kg). A scaled waistcoat of overlapping steel scales fixed to a leather lining was also designed; this armor weighed 11 lb (5.0 kg), fit close to the body, and was considered more comfortable.Source: https://www.youtube.com/watch?v=swbJ9sk942M