Utilizing a highly breathable and durable mesh, this pack is here for the long haul. The entire structure has a good bit of stretch, but we worked to find the balance of maintaining form while allowing plenty of movement in this design. This pack is excellent for running, hiking, biking, and more. The key to fit is to cinch down the sides first, then adjust the front per your desire. The front harness has a lot of adjustability while being super stretchy too. Mountain Bike: Extremely stable on your body across the choppy stuff, and we extended the shoulder area a bit to allow freedom of movement. 4 front pockets allow for quick access of your essentials on the fly. Running: Short runs or as long as you want to go. This hydration pack is loaded with features to take you any distance. Hiking: The conforming fit and quick access pockets paired with a very breathable frame means hiking bliss. Fit For Ladies: This pack is designed to be friendly with your curves. With multiple anchor points on each side and stretch elastic for the cross connect, you can configure it to fit your shape. The adjustability in sizing is very broad to cover nearly every size and shape. Fit For Guys: This will fit up to about a 52" chest. When loaded things will change a bit, but we took the front shoulder depth and made it deeper than the Vest Packs (in case you're familiar with that fit). So a tad more girth and more vertical shoulder room. Pack Details Pack Weight: - 270grams, 9.5oz. Dimensions: 10"W x 13" tall / Volume 6 liters. Bladder: HydraPak 2L (70oz) elite, with quick disconnect and blaster valve. Compartment 1: Bladder compartment Compartment 2: Main cargo Compartment 3: Zippered elastic pocket with secure key clip. Material details: Our stretch fabric is tough, abrasion resistant, & endurance designed. Shoulder pocket storage: Phone, gel, nutrition, electrolyte and more, both sides.