In 1873, Levi Strauss and Jacob Davis first introduced their classic blue jean. However, by 1890 their exclusive patent for riveted clothing had expired, meaning that other companies could use the same construction. In response to this impending competition, Levi Strauss & Co. printed the inside pocket bag with information about the garment’s originality and extra strong denim -- referred to as "XX". More significantly, they assigned it an identifying number – 501 -- which would evolve into a signature brand. With the 501® name, the jean was distinguished not only within Levi’s® clothing line -- which had grown to considerable size -- but also from other apparel on the market. This enabled retailers to easily order the product by number rather than by a simple description, which they had done in the past. Going forward, any product made with the same high-quality material was assigned a lot number beginning with 5 -- for instance, 506® for the iconic trucker jacket -- and we continue using these numbers today. Made with XX denim from the Amoskeag Manufacturing Company, the 501® Jean remained at the head of the class and set a new standard for American workwear. Levi's® Vintage Clothing has honored the original and recreated its characteristic details,from the riveted construction and button fly, to the original Two Horse leather patch.100% Cotton9 oz. Plain Selvedge Loomstate Denim (12 oz. after wash)Button fly. One back pocket with exposed rivets. Crotch rivet. Cinch for adjustable fit.