Do you want to earn the respect of fellow Stalkers? Do you want to build a team of loyal friends who will stick up for you in times of trouble? Do you dream of kicking some Duty ass? All this and many other opportunities awaits you if you join Freedom!
A paramilitary group dedicated to destroying the Zone, Duty consists mostly of ex-military personnel who were abandoned or stranded in the Zone during their missions, or while patrolling the Zone before The First Emission. They are secretly supplied by the Military with armour and weapons, and hence are one of the most well-equipped factions in the Zone. They have been at war with Freedom for a long time, since the two factions' beliefs completely contradict each other (Freedom wants free access to the Zone, Duty wants to block it off or destroy it).
I gotta say, Duty is very nice. After all, it's not every faction that literally puts bulls-eyes on their uniforms and patches for you.