Level 4 onyx body armor is a personal protection device that is designed to protect the wearer from a ballistic threat. Level 4 onyx body armor is made up of three different layers. It is designed to keep the wearer from being burned by the bullet. There are many different levels of armor that are designed to provide different levels of protection. The most common levels of onyx body armor are Level 1, Level 2, Level 3, Level 4, Level 4a, and Level 4b.