Abstract: An improved device for monitoring the presence of a person, animal or piece of property within a predefined space. The invention consists of a means for attaching to a monitoree, a transmitter assembly containing electronic circuitry which periodically sends a coded signal a limited distance to a remote detection unit. If the expected signal is not received, indicating that the person or object has been removed from the predefined space, an alarm condition is indicated. The transmitter is securely attached to the item being monitored by means of a non-stretchable, flexible, circuit strap which indicates an alarm condition when the strap is tampered with. The strap is locked into the transmitter assembly by a latch key which also triggers the transmitter to begin sending signals. The device is easily reattached or transferred to another item to be monitored by monitoring personnel by removing the latch key and inserting a new latch key after the device has been reinstalled.