About this item 1/4 inch MFL x 1/4 inch MFL Filter-Drier for use with Robinair RG3, RG6 and other refrigerant recovery machines Designed to be placed in line between inlet fitting on AC machine and outlet fitting on manifold gauge set Prevents contamination from entering the refrigerant recovery unit, which reduces the risk of damage to both the unit and the system being serviced If recovering more than one type of refrigerant with the same recovery machine, a separate filter drier must be labeled and used for each refrigerant type Sold individually