The sensing job is simple
Most contact sensors report open and closed states.
Mounting geometry matters
The two sensor parts must align within the manufacturer's specified range.
Battery reporting is useful
A device that warns early about low battery is easier to maintain.
Think beyond security
Contacts can also support lighting, HVAC reminders or accessibility routines.
Keep in mind. Compatibility is not permanent. Confirm the current manufacturer, platform and certification information before purchasing, resetting or migrating a device.