Our Metric Flangeless Male Nut is easy to use, eliminates the need to flange tubing and are reusable. It is made of It is made with versatile Delrin(acetal resin) which allows the nut to resist cross threading or loosening during use. It comes with a M6 Flat-Bottom port configuration and is for 1.8mm, 2.0mm, 3.0mm and 1/8 OD tubing.