Back systems motionfit trail sensifit pack adjustable sizing load management large twin link sensi compression pockets amp compartments 1 main compartment 2 front soft hydration elastic pockets 1 side stretch pocket 2 stretch front pockets 1 internal pocket 1 side zipped pocket carrying system custom system extra custom carrier 4d pole holder helmet loops security whistle reflective hydration soft 15l blue reservoir plug n play system under arm routing 4d bladder insulated sleeve blade