In the picks-and-shovels universe, Invitrogen and Sigma-Aldrich focus on chemicals and 'consumables,' the products that researchers use and then throw out. Some companies concentrate on instruments, and others offer a mixture. Diversified companies include Qiagen, Applied Biosystems and the biggest publicly traded life-science tool company, Thermo Fisher Scientific. Its market cap of $23.7 billion is triple the size of Sigma-Aldrich. Created in 2006 by the merger of Thermo Electron and Fisher Scientific, the Waltham, Mass.-based giant has unanimous buy ratings by the 10 analysts polled by Thomson First Call. Thermo "does not see an economic slowdown impacting the industry," says a February research report from Thomas Weisel Partners. Fourth-quarter results beat Wall Street expectations for the fifth consecutive quarter since the merger, says analyst Peter Lawson, who has an overweight rating. "Thermo's outlook for 2008 appears solid." He doesn't own shares; his firm says it expects to seek or receive investment-banking compensation from Thermo in the next few months. Thermo takes diversification well beyond its peers, providing products and/or services not only for medical and scientific R&D but also for industries as varied as beverages, coal mining, petroleum, semiconductors, cement and metals. "The company's diversified revenue base, which includes a large recurring stream of consumables routinely used in labs, lessens its exposure to pharmaceutical capital spending cycles," says Morningstar analyst Alex Morozov in a recent research report. "It does not appear that recessionary fears have affected its U.S. business," Morozov adds. "Its Asia Pacific business is growing gangbusters." However, with shares recently trading a just few dollars under Morningstar's fair value estimate of $59, Morozov breaks with the buy recommendations of sell-side analysts, by advocating a neutral three-star rating for Thermo.