Actually with regards to the bulletproof vest (the correct term is body armor) it depends on the vest; Class I to Class IIA vests are soft vest relying on kevlar layers alone; Class III and Class IV military vests use layered kevlar and a hard armor insert plate to defeat the incoming bullet. (Previous insert plates were made from steel but are now made from ceramic composites.) There's a cloth outer layer that's thin and holds the vest together. Bullet hits the cloth and then the first kevlar layers, then hits the insert plate and is stopped.
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