7/16" x 12" Hex shank extension for self feed saw tooth bits, auger bits and hole saws. extends your reach a full 12" inches. Fits three-jawed chucks, 1/2" drill chucks larger. Also fits 7/16" quick change chucks. We also have this in 5-1/2", 18" and 24" lengths. Call us today 1-800-350-8665 Ext: 100