he Flak Sack II is the world's toughest theft-resistant drawstring backpack. It's a backpack & a portable safe, all-in-one. Made from Flaknit, our virtually slash-proof fabric that achieves an A9 cut level, the highest there is! This lockable bag was designed to accommodate the lifestyles of people on the go who need their essentials with them, but are not able to be constantly looking after them. This bag doesn't just carry your belongings, it protects them.