Question: The company which is  a subsidary of the American footwear company founded by Charles Beckman is a principal supplier of what. 
Context: UGG is an American footwear company and a division of Deckers Brands. Vision Street Wear is an American footwear company which was founded by Brad Dorfman and is now licensed by Collective Licensing International.  According to the United States Patent and Trademark Office "USPTO.GOV" the word mark "Vision Street Wear" was first used in Commerce on April 18, 1986.  See Trademark Registration # 1506002. Charles Beckman (August 16, 1813 - January 9, 1892) was an American farmer and politician from Watertown, Wisconsin who held a number of public offices, from mayor to member of the Wisconsin State Assembly. Northside USA is an American footwear company based in Marysville, Washington.  Northside, a subsidiary of Triple T Trading, was founded in 1985 and sells shoes in retail stores in the United States and China.  The company's shoes, marketed towards "light outdoor recreation", are designed in the United States and manufactured in China. Lakai Footwear Limited is an American footwear company based in Torrance, California that creates shoes designed for and inspired by skateboarding.  Lakai was founded by professional skateboarders and Girl Skateboards co-founders Mike Carroll and Rick Howard in 1999.  Lakai Limited Footwear is part of the Crailtap Distribution along with companies Girl Skateboards, Fourstar Clothing, Royal Trucks, and Chocolate Skateboards. S.B. Foot Tanning Company is a leather production facility located in Red Wing, Minnesota.  It processes leather for use in the crafting of shoes, boots, belts, and leather accessories.  In 2010, the factory processed nearly 6 million linear feet of hides.  S.B. Foot Tanning Company is a wholly owned subsidiary of Red Wing Shoes Company, Inc. and is the principal supplier of leather to their shoe manufacturing plants.  The company also supplies over 1.5 million linear feet of leather for use in the production of military footwear per year, extending a tradition that began with World War I, when the tannery supplied boot leathers for the construction of soldier boots. Red Wing Shoes (Red Wing Shoe Company, LLC) is an American footwear company based in Red Wing, Minnesota that was founded by Charles H. Beckman in 1905. Sole Technology, Inc. is an American footwear company, specializing in skate shoe production and distribution.  The company is owned and run by Pierre André Senizergues, a former professional freestyle skateboarder.  The company's headquarters are in Lake Forest, California, United States (US). Kashi Kicks is an American footwear company based in Pittsburgh, Pennsylvania that produces unique sneaker designs.  Kashi Kicks was developed as a more fashion-oriented line compared to other brands at the time, in both aesthetic and function.  The shoes are endorsed by a number of members of the hip hop and professional athletic communities including George Clinton, Flavor Flav, Talib Kweli, Joey Porter, Nino Storm and Ginuwine. Merrell is an American footwear company founded by Clark Matis, Randy Merrell, and John Schweizer in 1981 as a maker of high-performance hiking boots.  Since 1997 the company has been a wholly owned subsidiary of shoe industry giant Wolverine World Wide.  The company recorded total sales of footwear and clothing of nearly $500 million in 2010.
Answer: leather