The Loctote Flak Sack is exactly what it sounds like. A sack with a lock. They are comfortable to carry and secure. You can’t even slash it open with a knife. They use a FLAKnit fabric which is exclusive and slash-proof fabric that’s virtually indestructible yet remains soft. The slash-resistant toughness comes from the superior cut protection of Honeywell’s UHMWPE Spectra fiber, which is the same fiber used in police vests and military gear. Oh yeah, your stuff is safe in one of these bags.