ESE

Esco Technologies Inc.

A maker of highly engineered parts for aerospace, defense, and power grids, Esco Technologies builds filtration and fluid-control components for aircraft, submarines, and satellites, along with diagnostic tools that help electric utilities check high-voltage equipment. It began in 1990 when Emerson Electric spun off its defense business, and the "Esco" name comes from that Emerson origin rather than any acronym. Fun twist: in the energy world, "ESCO" usually stands for Energy Service Company, a common source of confusion with this St. Louis firm.