These adapters fit the Ersa i-Tool soldering iron and will keep a small metal tube in place to attach to your solder fume extraction unit. There are two versions, one for 5mm tubing (e.g. 5x0.2mm stainless steel) and 6mm tubing. In the attached picture I used 6x0.5mm brass tubing and also modified the i-Tool holder to also work with fume extraction setup.