6 Liter; One size fits most; Includes 750mL flask and hose; Front: 5mm foam shoulder strap for comfort; Stretch stash pockets for glasses or nutrition; Removable Strap for left or right wearing; Additional run rtrap (with clip) removable when not using for running - built for a bounce free run; Main compartment features drawstring closure to adjust and maximize storage; Helmet compression flap designed to secure and compress load; Daisy chain for extra storage attachment; Back of body zipper for valuables (phone, keys etc); Side zipper for easy access to main storage pocket; Weight with flask: 9oz/255g; Weight w/o flask: 6oz/170g