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. Dimension details : Dimensions identical on switch and magnet Length : 33mm Width : 15mm Depth : 8.5mm Cable length : 300mm Mounting Method : Surface Attachment / Securing Method : Screw Down Overall Screw Spacing (H) : 18mm Packaged Volume : 0.03l Packaged Weight : 0.01kg Packaged Length : 7.5cm Packaged Width : 3cm Packaged Height : 1.2cm