Eagle trapped key safety interlocking systems from the Kirk Key Interlock Co. ensure users follow a predetermined sequence of operation for activating road, rail and sea tanker control valves in oil refining and other industrial applications. Each step in the scheme releases a uniquely coded key required to move safely to the next step. The oversized keys cannot be duplicated and the sequence cannot be circumvented. 800/438-2442; www.kirkkey.com.