**MP 66 (R-401B), an HCFC-based refrigerant from DuPont is an easy, quick, and cost-effective retrofit refrigerant for R-500 systems. It can also be used instead of MP39 (R-401A) for retrofit of low-temperature R-12 stationary positive displacement systems such as commercial freezers where higher capacity is needed. MP 66 (R-401B) is also used in some R-12 transport refrigeration equipment. ** Easy Retrofit: Works with existing mineral oil (MO) in many unitary and close-coupled systems. Alkylbenzene (AB) oil is recommended for optimum oil return. One compressor oil change to AB will typically remove 50% to 80% of the existing MO, which satisfies the recommendations and requirements of most compressor manufacturers. *MP 66 is a Registered Trademark of DuPont **Information above obtained from "DuPont Refrigerant Products"