These parts are insulating covers for a Raspberry Pi 5 when used with the PiDP-10 replica computer console. One insulator covers the network and USB ports to prevent shorts between the Pi and the LED circuit board and the other covers the underside of the Pi 5 circuit board to provide a flat layer for the PiDP Pi cover to lay on. The underside of a "stock" Pi 5 board contains many bumps and protrusions like test points, resistors and capacitors, solder blobs, uSD card, etc. The thin sheet will level all of that out so that the kit's Pi cover will lay perfectly flat. The USB cover part has fairly tight tolerances so slight adjustments may need to be made to ensure proper fit on your Pi 5 as there could be a few thousandths difference in how your Pi was soldered together.