4 ZERO CLEARANCE INSERTS CUSTOM MADE TO FIT DEWALT 7491 AND 7491RS. THE INSERTS ARE MADE OF MDF. ***NOT MEANT FOR USE WITH A RIVING KNIFE.****DO NOT BUY FOR DEWALT 7485 MODELS***. THAT MODEL HAS A DIFFERENT TYPE OF PLATE ALSO FOR SALE IN OUR SHOP.. SET SCREWS ARE INCLUDED TO ASSIST WITH LEVELING THE PLATE. ZERO CLEARANCE INSERTS ARE CALIBRATED TO A SPECIFIC SAW, A SPECIFIC BLADE, AND A SPECIFIC BEVEL ANGLE. THEY CAN ONLY BE USED ON CUTS WHERE THOSE PARAMETERS ARE MET. FOR EXAMPLE, ONCE AN INSERT IS MADE FOR A STRAIGHT-ON 90° CUT, IT CAN'T BE USED ON OTHER CUTS. IF YOU NEED TO MAKE A 45° BEVEL CUT, YOU CAN'T USE YOUR 90° CUT INSERT. YOU MUST HAVE A 45° INSERT, OR SWAP IN THE ORIGINAL THROAT INSERT. EACH ZERO CLEARANCE INSERT IS GOOD FOR ONLY ONE SPECIFIC BEVEL ANGLE.