Halon is corrosive, CO2 not so corrosive. Local price here for Halon refill is $18.75 per pound, CO2 is $1.13 per pound. A used 10 lb CO2 extinguisher cost me $35.00, a used 10 lb Halon is $145.00 (Yeah I know, the math does not add up at $18.75 per pound it should be $187.50 for a used 10 pounder). New........well lets just say I would rather use the money to buy a DF engine. Go with the CO2. Ken H