1 piece of polycarbonate (Lexan) sheet transparent measures around 300mmx200mmx3mm. The sheet will slide into the MakerBeam T-slot, MakerBeamXL T-slot or OpenBeam T-slot. Useful for more mounting options or if you want to encase your electronics. You can drill or saw the material. At the same time the material is solid enough to give you more mounting options. The material can also be used to encase your electronics.