The MMF-301 monitor module can be installed in a single gang junction box directly behind the monitored unit. Its small size and light weight allow it to be installed without rigid mounting . The MMF-301 is intended for use in intelligent, two-wire systems where the individual address of each module is selected using rotary switches. It provides a two-wire initiating cir- cuit for normally open contact fire alarm and security devices. This module can be used to replace an M301 module in existing systems.