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STH traces its origins back to the 1940s, when Samuel Alderson created the first ATD to test aircraft ejection seats, aviation helmets and pilot restraint systems. The technology of these early dummies provided the foundation for creation of automotive crash test dummies in the early 1960s. Through multiple mergers and name changes, STH emerged as the leading supplier of crash test dummies and related vehicle test and measurement products.

STH has also broadened its portfolio through targeted acquisitions. In 2001, the company acquired Boston-based HITEC Sensor Solutions. HITEC has over forty years of experience designing and manufacturing custom force, load, torque and pressure transducers and providing other strain gauging services. In 2012, STH acquired Sensor Developments Inc. (SDI) located in Orion, Michigan. SDI designs and manufacturers strain gaged based force and torque sensors, instruments and complete test systems. In 2013, the  STH was acquired by Golden Gate Capital, a private equity firm with over $12 billion in committed capital. Unlike conventional private equity firms, Golden Gate Capital operates as a private holding company and is dedicated to recapitalizing, restructuring and ultimately building meaningful businesses in partnership with management over an indefinite time horizon.

Golden Gate Capital is a San Francisco-based private equity investment firm with approximately $12 billion of capital under management. The principals of Golden Gate Capital have a long and successful history of investing across a wide range of industries and transaction types, including going-privates, corporate divestitures, and recapitalizations, as well as debt and public equity investments. Other notable industrials investments sponsored by Golden Gate Capital include US Silica, EP Minerals, ArrMaz, Springs Window Fashions and Atrium Windows. For additional information, visit

Recent acquisitions include the purchase of Austria-based FronTone GmbH, a leading provided of advanced safety testing equipment, in 2015 and Fibercore Ltd, the market leader in the specialty optical fiber sector, in 2017.

Today, STH is singularly focused on delivering superior test and measurement solutions with vision focused on the life-saving benefits of safety testing.