IDEX Flangeless Fittings systems are designed to include both a nut and ferrule for yIDEX convenience. Flangeless fittings are excellent replacements for flanged fittings. Flangeless fitting are dependable, easy to use and easy to replace. It has a 5/16-24 Flat-Bottom port configuration and is for 4mm OD tubing. IDEX Fitting System comes with the P-133.