Great double-sided pocket flasher from Sears, Roebuck and Co. for their Hercules Overalls. This flasher goes into detail about their Sanforized "Blue Blood" Denim. The "Blue Blood" method refers to indigo dying the yarn all the way to its core. There is no date on the piece, but I'd date it to around the 1940s.
Sears, Roebuck and Co. started using the Hercules name on products in 1908. Their first product bearing this name was a boiler. It appeared on goods such as work clothing, appliances and even insurance. The Hercules name made its last appearance on a bandana in the company's 1964-65 fall/winter catalog.