When dealing with body armor, it is important to know the difference between bulletproof and stab proof, as they both use different materials, have different characteristics and are suitable for different situations.
If you want to stop standard handgun bullets: Level 3A body armor
If you want to stop assault rifle bullets: Level 3 body armor
If you want to stop high caliber armor penetrating bullets: Level 4 body armor
Note: Atomic Defense Level 3A body armor also protects against 12 gauge slugs and buckshot