Sunday afternoons in August are for baseball. But in Houston, sitting in 105 degrees sunshine isn't fun, even if the Astros are winning. So Enron Field has a retractable roof and 42,000 fans can watch baseball in 70 degree comfort. Retractable roofs aren't uncommon on sports stadiums, but smooth operation has been something else. Enron Field, which opened in March 2000, was designed with three huge roof sections, thousands of tons each, moving on 142 wheels. To support the movement and loads up to 325,000 pounds, patented cylindrical springs were installed between the wheel assemblies and the roof sections. The springs, made of alternating layers of steel and Crompton's Adiprene® castable urethane, are key to the smooth operation of the roof. "There are many applications where urethane is the best and only material to use because of its ability to meet a wide variety of mechanical and environmental challenges," said Bruce DeMent, president of Kastalon Polymer Products, the company that designed and manufactured the nine-inch springs. Learn more at the following web locations: Kastalon Polyurethane Corporate site Astros.com Official Site Enron Field Learn more about the Ballpark