We now offer a limited edition variant of Wireless Tag Pro that uses 3D accelerometer instead of 3D compass to sense motion and door open-close (works only on vertical door like garage door and mailbox door). The benefits are

• Immediate notification: The accelerometer measures acceleration 10 times a second resulting in virtually immediate notification.
• Less false alarms: The accelerometer is not susceptible to electro-magnetic interference from nearby appliances turning on/off. This allows you to increase the sensitivity to detect small vibration, not possible with regular 3D compass based motion sensor tags. 
• Two types of motion event: "Moved" and "Carried away": The tag can distinguish short vibration that lasts less than a second from longer movement lasting more than 2 seconds. 

The battery life of the accelerometer based tag in default setting is similar to that of regular 3D compass based tag in default setting. 

UPDATE (May 12, 2021): We now offer a lower cost version of this, based on the temperature-only standard Wireless Tag instead of Wireless Tag Pro. It focuses on detecting motion, and does not integrate high resolution temperature / humidity sensor nor on-board memory like the Pro. This results in lower price and longer battery life due to the removal of components that are not core to your use-scenario.