A bag comprising a storage compartment crew of a port system

The invention relates to a bag comprising a storage compartment equipped with a carrying system having a strap (11) and a protective element (18) intended to be arranged resting on the shoulder of a wearer, said compartment having at least a sleeve (12) wherein at least one portion (13, 14) of the strap (11) is slidably mounted, said strap having two free ends (20, 21), the carrying system comprising a rotating association device the protective member (18) between said free ends.