HighFinesse started business activity with the product class Precision Current Sources. Today, the current sources are operated in quantum optics research laboratories all over the world for high precision control of magnetic field. The unique feature of the products is the use of analogue transistor technology which enables extremely low noise source currents. Bipolar sources with continuous tuning of currents are available in the range of 1 mA to 200 A. Our partner in current source development is the Prolan-Mat Kft.