You only need to know D371X-6C DN450. The previous DTs were made by some bidding companies. They all made the models weird and weird so that those who took advantage of them The leaders of the state-owned enterprises are easy to operate, as if no one in the world except his family can make this type of thing. In fact, it is an ordinary thing. If you see these various models more often, you will not be surprised in the future. , I don’t recognize it anymore. I worked for a company before, and they simply registered a patent. It’s just a damn ordinary thing. The only difference is that this model is only sold to PetroChina and Sinopec. It’s not sold to ordinary customers. They are exactly the same, but the model is different and the price is nearly double.