Bronkhorst High-Tech - Dutch thermal mass flow meter and controller maker
EGE-Elektronik Spezial Sensoren - Manufacturing sensors, including globally utilized thermal flow controllers, since 1976
Sierra Instruments - Founded in 1971. Manufactures high performance flow meters and controllers
Valco Instruments (VICI) - Manufactures precision-machined fixed- and adjustable-span aluminum and stainless steel flow controllers