His black riding suit resembled leather inlaid with titanium wire, but it was actually composed of flexible polymer fibers lined with sheer thickening liquid—a mixture of polyethylene glycol and particles of silica whose chemical structure stiffened instantly into a solid under rapid compression. In technical terms the gel displayed a highly nonlinear rate-dependent sheer resistance—which in layman’s terms meant it could stop a bullet or a knife while still being comfortable to wear.
