Whether your driveway gate is an automatic slide or swing gate, a magnetic lock adds another layer of security that is more than worth the increased cost of having one installed as part of an electric gate system.
Thinking Like a Villain
Chain drive slide gates are quite easy to defeat. A criminally minded person only has to hop the gate or fence and cut the chain to have full access to the property. The addition of a properly installed magnetic lock nearly eliminates the possibility of someone being able to open your driveway gate without authorization.
As covered here, swing gates are not as secure as slide gates, but with the addition of a magnetic lock, your gate is at least secured against a person pushing the gate open. Without a magnetic lock, a strong person very well may be able to push your gate open and get to the goodies within that you were hoping to protect.
How it Works
You've probably already surmised this, but a magnetic lock or maglock is a locking device that uses electromagnetism that is engaged by power sent to it from your gate operator when the gate is closed. Maglocks are only unlocked when you give the gate the open command with, for instance, a push of your remote or an entry on the gate's keypad.
A criminal intent on entering your property would have to spend the time required to unlock your gate operator and disable its power supply before being able to open the gate. The criminal's time would be better spent searching for a property with easier points of entry than suspiciously lurking about your home or office with a toolbox in hand.
Summing it Up
Without the installation of a magnetic lock your security driveway gate really isn't that secure.
Please, not magnetic locks are only suitable for electric mains powered gate kits.
High powered Magnetic Gate Lock