From the Manufacturer: This 120/240 volt Zinsco 40 amp, double pole, thin series replacement circuit breaker is used in a Zinsco load center. Typical applications, up to 8,800 watts, include electric baseboard heat, fan forced heat and 240 volt air conditioners (up to 23,000 BTU). These are only suggested applications and cannot assure compliance with all local codes. Please check local electrical codes before starting any electrical project. This 120/240 volt Zinsco 40 amp, double pole, thin series replacement circuit breaker is used in a Zinsco load center. Typical applications, up to 8,800 watts, include electric baseboard heat, fan forced heat and 240 volt air conditioners (up to 23,000 BT 3/4" ,40 amp 120/240 vac ,Non-interchangeable ,10 000 AIR ,Switch indicator ,Plug-in ,Fits Zinsco panels ,Standard overload and short circuit protection in Zinsco load centers ,ETL listed ,HACR rated ,Bulk