Universal Engineering Acura-Flex Chuck p/n 804290, Milling Collet Nut 901376, Includes 5 Positive Retention Type MILL Collets, (2) 1.250", 1", 7/8", and 3/4". Note the button that extends into the collet bore. Also included is a used 3.00" Spanner Wrench p/n 85296. Plus 7 Used Acura-Flex Collets, Sizes 7/8", 5/8", 19/32" (15mm), 9/16", 15/32" (12mm), 13/32" (10mm), and 5/16". Tools-n-gizmos.com has other sizes available.