They laughed at my magnifier.
One day, I visited a trade fair in China. At first, when I said, “Let me check the item,” and brought out my magnifier, they all laughed. But if you check the tip of a screwdriver closely, you can see what is wrong and coarse. Then, you can point out and fix the problem. Some differences in quality are visible, but many are microscopic. I didn’t want to sell anything that I didn’t like even if it made a profit. That was my policy.