The MAGNASPHERE MSS line of security sensors provides a solution to all of the the weaknesses and flaws of the reed switch contacts. Because the sensors incorporate a true Form B switch, they are installed in an Open Loop electrical configuration. This is the same configuration required for other life safety devices such as smoke and fire alarms, and has long been the recommended configuration by most knowledgeable security professionals. The unique Magnasphere BMS switch utilized in these devices renders the MSS products virtually unbreakable, and highly resistant to permanent contact welding and outsider magnet defeat, allowing Magnasphere to offer an industry leading product warranty. The MSS Series is UL and ULC listed.