IDEX Super Flangeless PEEK Ferrule w/Stainless Steel Ring is designed specifically to eliminate loosening of fittings due to tube twisting, hold tight even during vibration and delivers the highest pressure holding for flat bottom fittings that we offer. IDEX ferrule assembly has a M6 or 14/28 Flat-Bottom thread port configuration and is for 1/8OD tubing. It also comes in black as a single and in a 10 pack.