Enhance your security and automation projects with the MC-31B Magnetic Reed Switch Wired Door Sensor (PTT-MC-31B) , a professional-grade magnetic sensor designed for detecting when doors, windows,.This versatile sensor features both Normally Closed (NC) and Normally Open (NO) contacts, making it compatible with virtually any alarm system, security setup, or automation project The MC-31B operates using a simple but reliable magnetic reed switch mechanism: when the magnetic piece is near...