In Car Security
It's not easy to prevent a particularly determined or opportunistic thief from smashing a window in an attempt to snatch your hard-earned possessions from your car, but you can take steps to ensure that any such attempt is unsuccessful. GPS Satellite navigation systems and notebook/laptop computers are the items most commonly stolen from cars these days.
Tough Security Boxes
A lockable metal box chained to the car chassis, either in the boot or under the car seat is the best way to secure such items, or indeed anything else of notable value.