The Montana Brand 4-in-1 Drill & Driver provides versatility and ease-of-use for do-it-yourself tasks and professional construction projects. Drill, countersink or counterbore, then release the locking collar, flip the modular insert and drive the screw. Precision made for drilling accuracy and high-torque driving applications. Get jobs done easier, faster and with professional results. Items MB64857 thru MB64861 are the full units. MB65720 thru MB65722 are the counsink only. MB65727-000 thru MB65729-000 are the replacement drills. Also a great woodworking tool and companion set with the Montana Brand Self-Centering Plug Cutters. Legend (in inches unless otherwise noted): SHK = Shank SS = Screw Size Technical Info: Montana Brand quick-change drill bits sets, quick-change drivers, self-centering plug cutters, and other tools are manufactured utilizing proprietary state-of-the-art CNC machining equipment and the highest quality materials available. Montana Brand tools are guaranteed for life to be free of defects in material and workmanship because we build these tools with pride and determination.