This invention relates to an apparatus and retrofit method for integrating a safe into a security system, the apparatus comprising a wireless transmitter that transmits the condition of the safe to the receiver of a security system. The apparatus comprises at least one battery-operated transmitter in wireless communication with at least one receiver through an antenna concealed on the exterior surface of the safe and sensors connected to the transmitter. The design of the safe body and the integration with a wireless interface allows for flexibility and portability of the safe while maintaining strong security.