This stylish green beret reduces your soldier's noise by 10%. Don't ask why, it just does! Unlockable by the daunting task of a 100% recce. This is helpful, though not necessary, on stealth oriented Missions and can also be paired to great use with the Ho Chi Minh Sandals.
The Green Beret are an elite portion of the US Army Special Forces that operated in Vietnam; they were very effective as a special operations unit, though Green Berets and LRRP Rangers were separate divisions. This is somewhat of an homage to their stealthy (And sometimes not so stealthy) actions.