Mini-horns shall be a System Sensor Model MHRA or MHWA capable of operating at nominal 12 or 24VDC and shall mount to a single gang back box. Mini-horn shall be listed to Underwriter's Laboratories of Canada CAN/ ULC S525. Mini-horns shall operate between 0 and 49 degrees Celsius (32 and 120 degrees Fahrenheit) from a regulated DC, or full-wave rectified, unfiltered power supply. When used with the Sync?Circuit™ Module Model MDLA, 12-volt rated notification appliance circuit outputs shall operate between 9 and 17.5 volts; 24-volt rated notification appliance circuit outputs shall operate between 16 and 33 volts. Mini-horns shall have settings for Hi/Low volume and temporal/continuous tones. Mini-horns shall be able to operate from either continuous or coded NAC circuits.