PEEK (polyetheretherketone) fingertight fittings (short fitting set) are convenient, inert, and biocompatible. Use these fittings with 1/16 in. O.D. PEEK, stainless steel, titanium, Tefzel, or PTFE tubing. PEEK fittings are compatible with all HPLC solvents (avoid concentrated sulfuric and nitric acids), and can be used at temperatures up to 150° C. Unlike stainless steel ferrules, PEEK ferrules do not permanently lock into place on the tubing. This allows the interchanging of fittings with tubing and columns, from manufacturer to manufacturer (e.g. from Agilent to Waters), and still form a zero dead volume, leak-free connection.