Lead Foil is a material used by the UNSC for ships that traverse Slipspace. Lead foil is essential to Slipspace, and to deep-space travel in general, as it absorbs radiation and prevents it from harming the occupants of the ship. Lead foil is relatively fragile and prone to melting at extreme temperatures. Lead foil can be found on most UNSC ships, in addition to the Long Range Stealth Orbital Insertion Pods.