DELTA 17-924 Mortising Attachment with 1/4 Inch, 5/16 Inch, 3/8 Inch, and 1/2 Inch Chisel and Bit Sets Mortising attachment comes with four popular mortising chisel and bit sets 1/4-inch, 5/16-inch, 3/8-inch, and 1/2-inch set Also includes a handy carrying case that holds everything for easy storage Offers large 4-inch capacity under hold-downs, 2-3/4-inches from ends of hook rods to fence Also fits drill presses with quill diameters of 66-milimeters, 50.8-milimeters, 48-milimeters, and 38-milimeters The Delta Mortising attachment will only fit the below models: Use it with Delta models 11-980, 11-990, 14-070 & 17-900 drill presses and 11-090 radial drill press; and Searss model 21313, 21315 & 21317 drill presses.