Designed to be used with the J-19 Filter, our Bung Adapter easily converts any 2” bung opening on a 20- to 55-gallon steel drum to a ¾” NPT. Once the Bung Adapter is securely mounted on the drum, our J-19 filter can screw into the smaller ¾” threaded opening. Each 2” x ¾” Bung Adapter is made of durable plastic.