Absolutely tiny, these encapsulated reed/magnet switches with leads are ideal for home and car security. Their size should make them extremely easy to conceal so that potential thieves are less likely to disable them. Made from moulded plastic.

Reed Switch contacts: closed when both units are together (ie current flows), and open when apart.

Normally CLOSED (NC) per pair.

Contact operation: Contacts are closed cicuit when the magnet is alongside the switch. For alarm installation this is denoted as the "normal" state as the door/window is secure and the alarm is armed.