Abstract: An improved shield panel for use in the top shield of a rotary disc cutterbar equipped mower that features a twin sheet, vacuum formed plastic panel with a steel frame that interfaces with existing hinge and mounting structures on the mower to enable the plastic shield panel to directly replace a steel shield panel. Stiffening ribs formed into the plastic shield provide the necessary strength for the shield panel while the resiliency of the plastic material enables the plastic shield panel to better withstand impacts from flying debris generated from cutterbar operation. Molded receptacles in the exterior surface of the shield panels are configured to receive connectors for the mower front shield curtain and any stiffening members necessary for attachment to the mower. The predominate use of plastic reduces weight and lowers production costs compared to a comparable steel panel with a plastic protective liner.