Whiteside Screw Type Helix Mortise Cutter Arbor 1/2 in. SH x 5/16-24 TH is designed for use with Whiteside's Helix Mortise Cutters, which are sold separately. This versatile arbor can be used in both hand-held and machine routers, making it a flexible tool for various woodworking applications. It features a 1/4-28 end thread size and is crafted by Whiteside Machine Company, located in Claremont, North Carolina. The arbor specifications include a 1/2 inch shank size, a 5/16-24 end thread size, and an overall length of 1-3/4 inches, ensuring compatibility and precision in your mortising tasks. Model Number: HMA-1/2A