Plain Back 5C Collet Lathe Chuck Closer For Lathe Scroll & Pinion Precision Machined and Hardened Should be Used With Back Plate (Adapter) To connect with Your Specific Lathe Spindle Plain Back, Recessed 3.740" x 0.184" Deep Can Use Any Size 5C Collet From 1/16 through 1-1/8 Scroll and Pinion Design just like 3-Jaw Chuck, Operated With Chuck Kay.