A maglock is a locking device that consists of an electromagnet and an armature plate. There are two main types of electric locking devices. Locking devices can be either "fail safe" or "fail secure".
A mag lock or electromagnetic lock is a powerful magnet that is mounted to a door, gate, or barrier. This magnet is paired with a metal plate which is secured to the door or gate itself.
Mag locks range in strength from a couple of hundred pounds of force for applications where someone using brute force is not a concern, to magnets which will hold under thousands of pounds of force for sensitive areas.
Mag locks require constant power to remain locked. If they lose power, they can not keep the barrier secure by themselves. Battery backups can be used to keep mag locks secure during power outages in situations where there is no emergency power generator in the building.
Today's mag locks generally use very little power. Multiple mag locks can be kept in operation using less electricity than a conventional 60 watt light bulb. The amount of electricity used is mainly related to the holding strength of the mag lock.
Magnetic shear locks which are designed specifically for doors which swing both ways.