Invented in 1930 for use in telecommunications, later on adopted for security applications. Sadly, still the most popular in use today in security systems!
This new technology was invented in the USA in 2002 and was immediately applied to the highest levels of security.
Reed-based magnetic contacts are easily defeatable. A simple external magnet can mask the contact, effectively
disabling the alarm.
TSEC contacts are resistant to magnetic masking from outside the protected perimeter: any attempt results in an alarm.
The switches are made of glass, they are too easily broken and need to be handled with care.
Magnasphere switches are made of tough metal which is difficult to break before, during or after the installation.