Our Flangeless Nut is easy to use and eliminates the need to flange tubing. It is manufactured from versatile Delrin (acetal resin). This material allows the nut to resist cross threading or loosening during use. It's Flat-Bottom port is one of the most frequently used by equipment manufacturers. It has a 5/16-24 thread port configuration and is for a 3/16OD tubing. It comes in natural color.