Osprey Mk 4 and Mk 4A body armour has mostly been replaced by the Scalable Tactical Vest component of Virtus body armour, which is even closer fitting and lighter than the Opsrey Mk 4 and can have its level of protection scaled up or down to match the prevailing type of threat. The vest also features a quick-release mechanism to aid safe extraction from hazardous situations such as burning vehicles or drowning and a dynamic weight distribution system which, when linked to a soldier's waist belt, aids in spreading the soldier's load across the back, shoulders, and hips; a mechanism in the small of the back allows the wearer to adjust the weight bias depending on the situation.