Vango stone 20 day rucksack description ideal for everyday use such as day trips gym and walking the stone is also well suited as a back to school option to carry books and smaller items such as pens and pencils features airforce back system contoured channels create a chimney effect that enhances ventilation while active these channels are covered with highly breathable airmesh offering a great back system for medium capacity packs shaped adjustable harness for optimum fit