Armor-piercing bullets came into use as early as World War I. The development of the KTW bullet known as a cop-killer bullet resulted from requests by police in the early 1960’s for bullets that could penetrate the protective armor worn by terrorists. Soft body armor has improved greatly through the use of new fibers and designs that provide better protection in a much lighter and more comfortable package. However, most concealable models used for daily wear still are not designed to stop rifle rounds. At the same time, the average threat that police officers experience has increased. Police agencies should specify at a minimum that bullet resistant vests stop the Winchester Ranger 9mm +P+ 127-grain SXT bullet used by many police agencies. Ammunition has evolved over time; the Five-SeveN semi-automatic pistol introduced in 1999 by FN Herstal of Belgium consistently penetrates 48 layers of Kevlar. Body armor has also evolved and moved from ballistic nylon in 1937 to Kevlar 29 in 1973, Kevlar 129 in 1988, SpectraShield and Twaron T-2000 in the 1990's, and Zylon. Zylon offers at least 6 percent higher strength and protection and nearly 40 percent lower weight and thickness than the other materials. The industry will probably use it in composite vests in the near feature due to its cost. Photographs