it removes the pipe kinda thing that is out of place when your weapon is equip 
its just for males btw because female one doesnt have the problem that makes the pipe thing way out of the place when your weapon is equip 

after downloading this, go to (fallout 4 folder)--->data--->meshes--->DLC03--->armor--->combat armor, and then extract it there, and yes you have to replace the existing torso file there so ye