Business was booming. In 1856, the older brothers of the Left, who bore the American names Jonas and Louis, joined the company. A sign "Levi Strauss & Co" was installed at the store on Sacramento Street, indicating that the place belongs to Strauss and the company of his partners. Levi traveled around the mining camp, talked to customers right at the workplace and found out what they would like to change in jeans. Every detail was brought to perfection, so the demand for Levi's products exceeded the supply. At first, all the jeans were the same size, which meant fitting the figure after washing.
For a long time Strauss and partners supplied the material to other tailors. One of these clients, Jacob Davis from Nevada, in 1872 addressed a letter to Levi Strauss & Co. According to him, buyers of trousers complained that pockets were torn from heavy nuggets. Davis suggested Strauss to «strengthen» the material with double stitching and install rivets at the tension points. On May 20, 1873, the company received a patent. So the first jeans appeared.