The Ultimate Direction Scott Jurek Race Vest was designed by the World-renowned ultra-runner Scott Jurek. He designed the SJ Ultra Vest to be the ultimate pack for any occasion. Featuring the best volume to weight ratio of any pack ever made, the 7.5 ounce SJ Ultra Vest can carry a half-day of gels or bars in the easily accessible front pockets, along with a unique expandable or compressible main compartment utilizing Cuben-Fiber, for a total capacity of an amazing 9.2 liters. Options to carry trekking poles and an ice axe complete the package. Smart phone compatible pouches (2)Bottle holsters tighten to carry camera, ect.Gel or bar pouches (4) Electrolyte or valuables pocket (2)Fully adjustable Sternum Straps (2)Emergency whistleCuben Fiber bellows for large or small loads Secure Lat Pockets, with full pocket behind (2)Two sizes main compartments Hex Mesh for maximum breathability Trekking pole (2) and Ice Axe loop (1)Sizing At Chest (Unisex):SM: 25 - 31 in. / 63.5 - 78.7 cm; MD: 31 - 38 in. / 78.7 - 96.5 cm; LG: 38 - 43 in. / 96.5 - 109.2 cmMeasure wearing the clothes you intend to wearA vest full of gear will fit smallerVolume Capacity: 47 in.3 / 9.2LFluid Capacity: 2 x 20 oz. bottles / 2 x 591 mL Weight: 7.5 oz. (13 oz. with bottles) / 212 g (368 g with bottles)Height: 12 in. / 30 cmWidth: 9 in. / 23 cmDepth: 2.5 in. / 6 cmCuben Fiber: Used for the sails of America's Cup racing yachts, this non-woven fabric is 15 times stronger than steel and 40% stronger than Aramid fibers, and is extremely resistant to moisture, UV, and chemicals Hex Mesh: The structure of the vest is totally breathable, while also being extremely strong, lightweight, and will not absorb moisture.Power Mesh: All pockets and super stretchy, so small loads won't bounce and the vest expands as you need it to.