THIS MICROBORE 50CT-S200E02 SHELL MILL ARBOR IS DESIGNED FOR CAT 50 TAPER APPLICATIONS. TECHNICAL SPECIFICATIONS INCLUDE A 4-INCH PROJECTION, A 1-INCH BORE DIAMETER, AND A BODY DIAMETER OF 4.375 INCHES. THE OVERALL LENGTH WITHOUT THE BUTTON MEASURES 8 INCHES, AND 9 INCHES WITH THE BUTTON.