Scrith, forms the walls and floor of the Ringworld. Scrith is milky-gray translucent in color, and is a nearly frictionless material. The fairly thin layer of scrith that forms the floor of the Ringworld blocks the passage of 40% of the Neutrinos that encounter it, equivalent to almost an Earth-lightyear of lead. It also absorbs nearly 100% of all other radiation and subatomic particles and rapidly dissipates heat. The tensile strength of scrith is theorized to be similar to the Strong nuclear force, with the Ringworld foundation only measuring about 30m (100 ft) thick. It is transparent to magnetic fields.