Leakguard has been rigourously tested for stability and compatibility and is completely safe and effective with all types of refrigerants. Use leakguard as a preventative maintenance service to ensure against future leaks and extend the life of the air conditioning system leakguard permanently and safely seals a/c leaks in both rubber and metal components. It works by seeking out the oxygen present at the leak point. When combined with the pressure in the system leakguard is pushed through the leak causing it to congeal and form a permanent chemical weld at the leak point. Unlike other a/c sealants. Leakguard does not have any of the dangerous side affects. Because leakguard is an oil based sealant it will not harden crystallize or clog the a/c system or harm the recovery equipment. It is specifically formulated for slow leaks that can occur over a 6 - 12 month period (or a leak rate of 25 oz. (708 g) per year).