Brass Compression Fitting For Plastic, Copper, & Aluminum Tubing, 0.50 Inch Tube OD To 3/8-18 Male NPT, Straight

For plastic tubing, you'll want to pick up an Eaton PT230 insert along with the 2030 insert to keep everything compatible and properly supported. The fitting itself handles the compression connection, but those inserts are what hold up the tubing wall so it doesn't deform under pressure. Without them, plastic tubing can collapse at the joint over time. For copper or aluminum, no inserts are needed.