IDEX PEEK Super Flangeless Ferrule 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. Manufactured from biocompatible PEEK it offers excellent chemical resistance. This ferrule can be used with a 1/4-28 or 10-32 Flat-Bottom port configuration and is for 1/16 OD tubing.