We developed these tools for cutting accurate neck joints for a traditional Martin dovetail. Each custom made cutter bit is carbide-tipped for long life, with a 1/4"-diameter shank and a 1/2" guide bearing. A small length of heat-resistant tubing is supplied with the cutter bit to keep the bearing from riding up the shank. Designed for use with our Acoustic Neck Joint Routing Templates (sold separately). Dovetail bit specs: Overall length 2-9/16" (65.09mm) Shank length 1-1/2" (38.10mm) Maximum cutter diameter 9/16" (14.29mm) Cutting length for 10-degree dovetail angle 13/16" (20.64mm)