Mandible guard

A helmet assembly (100) having a helmet (102), a mandible guard (104) having a mouth covering portion, and an accessory attachment system (106) that is used to selectively attach and secure the mandible guard to the helmet is disclosed with removably attachable first and second attachment arms (108a, 108b) each extending from a helmet connection region to a mandible guard connection region. The mandible guard is arranged to be detached from a first side of the helmet while remaining secured to a second side of the helmet. The mandible guard may be moved outwardly and away from a wearer as the mandible guard pivots around the accessory attachment system attached to the second side of the helmet. When the mandible guard is secured onto the helmet via the two attachment arms, movement of the mandible guard inwards is prevented and the mouth covering portion maintains a protective position aligned with a midline of the helmet. When the first attachment arm is attached and the second attachment arm is detached, the mandible guard is movable out of the protective position. The mandible guard disclosed enables easier access to the lower half of the user's face but also allows quick, single-handed reattachment for use in high risk environments.