Nathan QuickStart 6L Hydration Vest Pack One Size Fits Most. Backpack for Men and Women. FUNCTIONAL – QuickStart is equipped with front storage pockets with one zippered pocket for phone, keys and other valuables. One front pocket fits a 22oz flask (not included). Main back zippered pocket for all essentials. FIT – One size fits most, with adjustable front and side straps for a perfect fit. Vest fit is snug and overall sizing tends to run slightly on the smaller side, so it is recommended that anyone on the higher end of a given size may want to size up! MEN or WOMEN – Versatility is key. Designed and built for everyone. Soft perimeter binding prevents chafing. DESIGN - Lightweight and comfortable mesh material that wicks away sweat and water. No bounce, No chafe binding, Reflective visibility. For running, hiking, walking, ridding etc. EUC. Used twice, just does not fit my body right. Let me know if you need a water bladder! I have one I can include it’s just not the original one