U.S. Products, a Coeur d'Alene manufacturer of commercial carpet-cleaning equipment, has been sold to a Danish firm – a move that will help the company sustain its rapid growth, officials said. The company makes high-end cleaners, retailing for $1,000 to $6,000 apiece. ServiceMaster, which cleans 10.5 million homes and businesses each year, is one of U.S. Products' customers. Company sales have quadrupled to $12 million in the past eight years, while the work force has nearly tripled. "Every place there's carpet, basically we're there," said Chuck Wilke, U.S. Products' chairman.