A Chevrolet Equinox fuel cell electric vehicle sits outside Air Products & Chemicals Inc headquarters in Allentown, Pennsylvania, U.S., on Tuesday, May 11, 2010. John McGlade, chief executive officer of Air Products & Chemicals Inc., said he won't raise his company's $5.1 billion offer for Airgas Inc. unless the target's management agrees to negotiations or a rival bidder emerges. Photographer: Bradley C. Bower/Bloomberg via Getty Images