The Bosch TS1005 zero clearance insert for table saw model 4000 is basically used for precision cuts at 90°. It reduces kerf clearance to thickness of blade. Features: * Use for precision cuts at 90-degrees and reduces kerf clearance to thickness of blade * Supports the work-piece closer to blade for less chip-out and splintering * Reduces kerf clearance to the thickness of your blade * Keeps blade clean by stopping sawdust from falling into the throat What"s In the Box: * Bosch TS1005 Zero Clearance Insert for Table saw Model 4000