This NSK Torque Type Attachment for the Espert 500 system is used with a ø1/4" chuck diameter with a special contoured hand-grip.• Collet Chuck Standard Size: ø1/4" (CHG-6.35)• Weight : 3.88 oz.• NSK Catalog Number: ES41552Includes:• Collet Chuck ø1/4" (CHG-6.35): 1 pc.• Wrench (10 x 10) : 1 pc. • Bar Wrench (K-212) : 1 pc.