IDEX Flangeless Lock Nut is designed to be used with yIDEX 1/4-28 male Flangeless fittings. It holds IDEX fittings securely in applications where there are vibrations that can loosen fittings. It is made of It is made with versatile Delrin(acetal resin) which allows the lock nut to resist cross threading or loosening during use. It comes in white.