Simply answer, Supor's double valve can control two kinds of pressure, and a single valve can only control one kind of pressure. Take a chestnut as an example: it may take little pressure to make fish soup, but it takes a lot of pressure to stew beef, so the control of the double valve is very simple, which can be realized directly through the first pressure and the second pressure. But the single valve can only be realized by gap heating to prevent the pressure from being too high. Of course, double valves are better. Supor adopts ceramic core pressure limiting valve for both single valve and double valve, which should be the highest-end valve at present, with excellent sealing and service life. It can be said that the pot is broken and the valve must be good. It can be said that Supor's products are really genuine. Midea, Jiuyang and other manufacturers use pressure-limiting valves with silicone cores. There is no problem with this product just bought back. After a long time, under the high temperature and high pressure of the product, the silica gel will age and the aging valve will start to leak. Of course, the valve core will be broken and its service life will not be long. I hope it will help you understand.