Knurled fitting for UHPLC connections. Must be used with EXP titanium/PEEK hybrid ferrules. The ferrule is not permanently swaged to the tubing so it is reusable multiple times. Hand-tight to 8,700 psi and wrench-tight (7/16") to 20,000 psi. When using a wrench, for best results, tighten a maximum of 1/4 to 1/2 turn past hand tight. For 1/16" OD stainless steel tubing. Replacement ferrules are REST-25935 (ea) or REST-25936 (10/pk). Not recommended for use with PEEK tubing. Replacement for 220-91522-35.