Most storage devices that do not require vision and a brain to read data fall into this category. Electromagnetic data may be stored in either an analog data or digital data format on a variety of media.
Direct Tripwire Alarm - The wire placed across the path is directly connected with the cord, wire or string placed across the particular path. Laser Tripwire Alarm - An invisible laser, typically an infra-red, is used instead of a cord or string.
Electrical metallic tubing is not threaded, and must be connected to junction boxes and the like with conduit connectors that secure to the tubing by means of a set screw or collet and nut; then the connectors have integrated shoulders and threads that secure to the box with a nut.