Reed relays are the design-in choice in most security systems; they are used in the passive infrared sensors (PIRs) as the main switching device and are used in the alarm call-up circuits. Many battery operated instruments use reed relays as a safety relay in its normally closed position where it draws zero power until called upon. Additionally, reed relays are used throughout industrial and robotics applications, in many switching applications and matrices. Explosion proof environments require the most reliable switching devices with no exposed arcing, the reed relay is a design-in favorite.