For Donald''s praise, Wang Bin had no burden in his heart, but nodded with a smile. Yes, these screw rods made of special glass are indeed as beautiful as works of art.

    "How''s it going? Mr. Donald, how do you feel about these screw rods? Do you need to buy some.

    I think you know very well about the performance of the glass produced by Tiangong technology, so I don''t want to say much about the quality. Let''s talk about the precision of these screws!

    Let''s take a look at this ball screw with the highest precision, which is the second-class precision screw in my world! Its precision has reached every 300 mm length, and the error is no more than 4 microns! By the way, I think you must know what the concept of micron is, so I won''t say more.

    Even if such precision screw is placed in our world, it can not be manufactured by any company or country. I won''t say the importance of such precision screw to machine tools and other equipment. I think you must know... "Then Wang Bin opened the flicker mode and introduced this screw with fragrance.

    "Mr. Donald, such a screw rod is only sold for 10 energy coins. It''s definitely worth it. Mr. Donald, don''t think about it!" finally, in Donald''s expression, Wang Bin introduced the screw rod.

    However, Donald was obviously not fooled by Wang Bin, but bowed his head and remembered that although the precision of this screw rod is absolutely very high for his world, and even his country has been called the world''s top industrial power, they can''t process such screw rods.

    But is such a precision screw really useful to his world? This made him some doubt. After all, such accuracy has exceeded the limit of his world. If there is no matching machine tool, the performance of these screw rods can not be played at all.

    Seeing Donald''s hesitation, Wang Bin introduced Donald: "since Mr. Donald is not satisfied with this screw rod, let''s take a look at the others, that is, the one in my hand. This is a screw rod with three-level precision at the top of my world, and its precision is eight microns. I don''t know how Mr. Donald feels!" Wang Bin picked up a three-level precision screw rod and said to Donald.

    However, after listening to Wang Bin''s words, Donald still didn''t speak, so Wang Bin picked up a four-level precision screw rod and said to him, "Mr. Donald, since you are not satisfied with this, take another look at this. This is a four-level precision screw rod with a precision of 12 microns, that is, 0.012 mm."

    Then, before he could speak, he picked up a five level screw rod and continued, "this is a five level screw rod with a precision of 23 microns, that is, 0.023 mm." soon Wang Bin introduced these screws to Donald.

    As for the lower precision screw rod, Wang Bin did not manufacture it, so naturally it did not exist in the mall, because Wang Bin did not think that it was meaningful to sell the lower precision screw rod in the mall.

    After all, as long as the visibility of civilization reaches level zero, it should not be a problem to manufacture such a precision screw rod in the later stage of civilization.

    After listening to Wang Bin''s introduction, Donald didn''t speak for the first time. Instead, he quietly considered it for a while before he said to Wang Bin: "shopkeeper, first give me ten secondary precision and one hundred tertiary precision screw rods. I''ll take them back and try them first. If I can, I''ll place more orders."

    "OK! Yes, said Wang Bin." soon, Wang Bin picked up ten secondary precision and one hundred tertiary precision screw rods, handed them to Donald, and said to him, "Mr. Donald, I hope you can be satisfied with these screw rods. Of course, if you can, next time you come to our Tiangong technology store, you can bring the use data of these screw rods."

    "All right!" said Donald.

    With that, Donald left Wang Bin''s shop and returned to his own world.

    What Wang Bin doesn''t know, however, is that the ton of glass he sold to Donald has made Donald''s restless world more turbulent.

    .......

    Donald William''s world is a ten thousand word country in the world during the Normandy invasion.

    In a huge underground base, Donald''s room, which was originally empty, suddenly appeared in the room.

    Back in his own world, Donald''s reaction was the same as that of most people. First, he looked at his room for a while and found that there were no people in his room, nothing had been moved, and nothing on the door had changed. He was relieved, which showed that no one had come to his room when he went to the technology mall to buy materials.

    So he tidied up his clothes, opened the door of his room and went out.

    As in the past, the whole base is full of patrolling soldiers, especially near his room and nearby warehouses and manufacturing workshops.

    Donald did not respond to this, because all this is very normal. In fact, in this world, no one knows that he has special abilities, including a very few senior leaders in his country, such as their head of state.

    Even his base is specially prepared for him. There are no more than ten people in the world who know the base except those in the base.

    After walking out of the room, when he walked in front of each soldier, these soldiers would salute him respectfully immediately, and then shouted long live the world, and he would salute naturally.

    Soon, he came to the material warehouse not far away.

    "You go out first!" he said to the guards after he entered the warehouse and saluted each other.

    After listening to Donald''s words, the two soldiers in the warehouse immediately turned around and walked out of the warehouse without any hesitation. After all, Donald is the boss in the base, and no one dare to disrespect him.

    But neither Donald nor anyone else in the warehouse found that among the soldiers who came out of the warehouse, one of the soldiers'' pockets was abnormal and slightly protruded. It was obvious that there was something in his pocket, but he couldn''t see anything in the pocket.

    Yes, what this soldier has in his pocket is the special glass that Donald bought from Wang Bin, and it is also a square piece of glass with a thickness of only 1mm and a size of 50mm. It is obvious that this soldier is not an ordinary soldier, but someone with ulterior motives lurking in his base.

    Of course, if it''s anything else, it''s easy to find, but this glass is different. Because the light transmittance of this glass is more than 96%, and the thickness is only a millimeter, no one can find it in his pocket.

    Donald has a lot of materials in this warehouse. If Wang Bin is here, he will find that many things in this warehouse can not be produced in Donald''s time.

    For example, a pile of steel in the warehouse can never be produced in this era, because these are not others, but some titanium alloy steel, but the quantity is a little small.