Some brands include TSA-approved locking systems and padlocks, making it easier for the user to open up the backpacks at checkpoints, security areas in airports, border crossings, etc.  There are also anti-theft backpacks available in the market, which have structures and flaps that hide zippers, making it extra tricky for inexperienced users to access specific compartments. Certain tech features like hidden security whistles and RFID safe pockets are present in some of the backpacks.