Kevlar body armor costs $650 and reduces damage taken by bullets and grenades.
Players can also buy kevlar armor with a helmet for $1000 that saves players from one-shot kills to the head by any weapon except sniper rifles, close range shotguns, the Desert Eagle, and the AK-47.
Damage from HE Grenades, buckshot, 9mm rounds, and .45 ACP rounds (i.e. most pistols and sub-machine guns) is reduced by approximately half.
Damage from rifle rounds and the armor piercing FN57 ammunition (used in the Five-seveN and P90) is reduced only by about 25%, although it should be noted that the FN57 ammunition does little damage in the first place. As long as you have any armor at all, the exact armor value does not matter. It should also be noted that Kevlar will not protect you from attacks landed anywhere other than on the chest, stomach, and head (with a helmet) hitboxes.
The hotkey for this equipment is b81/b82 or o1/o2.
Kevlar vest protects chest, stomach and arms (starting BETA 1.2) while helmet only protects head.