Filter/dryer is used on Several A/C service units, such as early EEAC313 models including. This is the filter/dryer that should be changed regularly depending on usage of unit. Designed to protect recovery systems from debris and deposits that would normally harm your unit. Large filter capacity provides long life. All steel construction with enamel finish resists corrosion and rusting. 1/2" ACME fittings are standard.