Nathan quick start 2.0 6 L running hiking black/blue hydration vest pack Unisex adults, XL condition, $100 retail, unsure if they sell this style or color way anymore, but they do resell for around retail price! One size I believe to be safe, fits up to an adult large unisex Very lightweight, 1.5L hydration bladder, easy, access, storage pockets, and adjustable straps.