Scentry III-SFGVC Gas Safety Device For Natural Gas or Propane Appliances Safety First USA Scentry III-SFGVC explosive gas monitor and gas valve controller. Senses and then controls dangerous gas build-up by turning off gas to protected gas appliance. Or to main gas line. Safety First USA Scentry III Gas Valve Controller shuts off a Scentry gas valve not included if an unsafe condition occurs. Gas sensor and valve controller in one box.. Note Gas valve automatically closes when the power goes off. N o option for a battery back-up. Cannot add additional remote sensors. Made in USA No external 24 volt transformer and no gas valve are included . Built in 90db alarm. Gas valve automatically closes when the power goes off. Gas control valve actuator does not include the gas valve. Scentry III-SFGVC Safety First Gas Valve Controller Case is bone colored ABS plastic. Physical size is 4.6 inches by 3.1 inches. Weight is .5 pounds. Manual reset. Output Control Relays are 4 amp, 24VAC with power of 1.5va. Sensor tin dioxide semiconductor. Connections use screw terminals. Propane alarm point is 5200 PPM. Natural gas/methane alarm point is 12,200 PPM. Requires UL Listed Scentry III or similar diaphragm type gas valve in .5 inch, .75 inch or 1 inch size. Requires 24V transformer not included that matches transformer to power requirements of valve. Note there is no option for a battery back-up nor an option to add additional sensors at a later time. Made in USA. This item ships from a separate warehouse and may require extra time for delivery.