THIS IS A JACOBS 36-3 TAPER BALL BEARING CHUCK FEATURING A 5MT – 3JT SLEEVE CONFIGURATION. IT IS DESIGNED FOR PRECISE DRILLING TASKS AND HAS A CAPACITY RANGE OF .18 TO .80 INCHES (5 TO 20 MM). THE OVERALL LENGTH OF THE ENTIRE PIECE, INCLUDING THE CHUCK AND SLEEVE, IS 9-1/2 INCHES. THE ITEM COMES WITH A CHUCK KEY.