 Hydrogen-powered aircraft, there's two approaches here. There's like a direct hydrogen combustion using just a burning hydrogen as if it was a jet fuel, for example. However, the approach we're taking for now would be a hydrogen fuel cells to provide power. So if we have a hydrogen fuel, it gets plumbed into the fuel cells. The fuel cells reverse electrolysis reaction happens. So hydrogen reacting with oxygen in the ambient air, it produces electricity. And that electricity gets sent into electric motors, and those electric motors then turn on a propeller, for example, thus providing the thrust that needed to power the aircraft.