The laser etched Jordco® e-Ruler® instrument is worn on the clinician’s finger. The e-Ruler product includes a finger ring, and can be used independent of the EndoRing® product. The ruler’s markings are precisely laser etched providing enhanced contrast for accurate and easy calibration of endodontic hand and rotary files. Each package contains: 3 finger rings (small, medium and large) 1 metal 30 mm ruler with rubber stop locks - OR - 1 metal 30 mm ruler without rubber stop locks Options include With or Without Rubber Stop Locks. Country of Origin: USA Non-Latex