With a diameter of 1/4", this lightweight stainless steel collet socket handle causes less finger fatigue. Is easy to position and pass to your assistant. It comes with a ruler to allow measurement of file lengths to within a quarter of a millimeter while working under the microscope. The exceptionally easy to read markings allow for very accurate measurements. Special surface treatment dramatically reduces glare from the microscope light making the markings easy to read. Order for your flexible mirrors. Only for use if you are right hand dominate and hold the mirror in your left hand.