THE ETM ER SPRING COLLET CHUCK AND SET INCLUDES AN ER40 COLLET CHUCK WITH A 2.156-INCH PROJECTION AND A CAT 40 HOLDER. THE NUT DIAMETER IS 2.48 INCHES, AND THE OVERALL LENGTH OF THE CHUCK IS 5-3/4 INCHES. THE SET COMES WITH A WRENCH AND 15 ER40 COLLETS. THE HOLDER LENGTH IS 2.5 INCHES, AND THE COLLET SIZE IS ER40.