RT adjustable compression fittings have a stainless steel body and cap with a PTFE ferrule.  The PTFE ferrule allows for tightening without crimping the probe sheath and allows the fitting to be loosened to change the probe or adjust immersion depths.  Available in sheath sizes .063”, .125”, .188” and .250” and thread sizes of 1/8”, 1/4" and 1/2" NPT.