Tesla has applied for a patent on a new “ultra-hard” steel alloy that it plans to use with the Cybertruck electric pickup truck.

The automaker, according to a report, plans to build the Cybertruck with a body and “exoskeleton” made of ultra-hard stainless steel. Tesla aims to develop its own alloy for the project and now has applied for a patent to secure the intellectual property behind it. In the patent application called “Ultra-Hard Cold-Worked Steel Alloy,” the company said that it could be used in a vehicle with an exoskeleton.