What is the magnet for? Jon Dennis Cruz October 05, 2021 08:36 The magnet and the sensor work together to monitor entry. If you are monitoring motion only, you do NOT need the magnet. Related articles I’m getting false alarms. How can I get rid of them? When would I use the Kangaroo button? What does "sensors left open" mean? How do I mount my sensor for monitoring entry? How to reset Motion+Entry sensor Comments 0 comments Please sign in to leave a comment.