The Sherline 3.1" 4-Jaw Self-Centering Chuck Coated w/ Master & Pie Jaws features a durable 12L14 steel body with an Electroless Nickel-Teflon coating, offering enhanced rust resistance and lubricity. This chuck is designed for precision work, particularly in ornamental turning and horological applications, with pie-shaped jaws that provide a full grip around the diameter of the part, reducing clamping pressure and deformation risk. The chuck accommodates jaw capacities ranging from 3/32" (2mm) to 1/2" (38mm) in normal position, and 3/32" (2mm) to 2-3/4" (70mm) in reverse position, with a through-hole diameter of .687" (17mm) and a thread size of 3/4-16. Included are a 1/4" x 1" steel dowel pin, a 1/8" hex key, two spindle or 'Tommy' bars, and 4-40 x 3/8" jaw mounting screws. Note that the jaws are designed to be bored to size for specific tasks and may require replacement over time, with the replacement set P/N 1143-4P compatible only with the 1076C Nickel-Teflon coated chuck body and master jaws.