One of many large light-blocking squares tethered together in orbit around the star whose system is home to the Ringworld. These objects function to block daylight from the Ringworld's surface to differentiate between day and night. They were originally also capable of beaming power generated by immense Solar collection to the surface of the Ringworld, though the Superconducter [1] The square and perhaps the cables that connect them are made of a dense and strong material called Scrith.[2]