From the company website http://www.burlingtonsocks.com/Kayser-Roth.aspx:
Burlington® is licensed by one of the most successful sock, legwear and intimate apparel manufacturers in America, Kayser-Roth Corporation.
Kayser-Roth Corporation is a major marketer of socks, hosiery and intimates products in the United States. Kayser-Roth is headquartered in Greensboro, North Carolina and operates four plants in North Carolina and Tennessee. The company also has a design studio/showroom in the heart of the fashion district in New York City. Within the retail industry, Kayser-Roth is regularly honored for its service, innovation and response to customer needs. Along with Burlington, other brands within the Kayser-Roth family include HUE, No nonsense, Calvin Klein, Prima Sport, Interwoven and many private label brands for major retailers around the country.