A ballistic vest or bullet-resistant vest, often called a bulletproof vest, is an item of body armor that helps absorb the impact and reduce or stop penetration to the torso from firearm-fired projectiles and shrapnel from explosions. The vest may come in a soft form, as worn by many police officers, prison guards, security guards and some private citizens. Prison guards and police may wear soft vests designed to resist stabbing attacks, using metallic or para-aramid components. Some Hostage Rescue Teams, and special mission units wear hard armors, either in conjunction with soft armor or alone. This allows for protection against rifle ammunition or explosion fragments.