The vest itself is modular, allowing for ammunition magazines, drop pouches, canteens, etc. to be added for mission requirements. It also features a holster for a sidearm.
SSgtAvery Johnson and SSgtNolan Byrne used ballistic assault vests throughout the duration of the First Battle of Harvest, though they are not effective against plasma weaponry. This is because ballistic gear is designed for defense against projectile weapons, such as the ones used by the UNSC. After the war humanity seemed to don this type of protection once again despite its ineffectiveness against plasma.