The company's reputation has grown from the Barnet Deadweight Testers (DWTs) back in the 1930's to the present where the company manufacturers a wide range of pressure calibrators and systems from low cost indicators to 0.008% primary standards.

SI recognized that offering only measurement devices was insufficient to meet customer needs. Pressure generation and control was equally important to produce an effective pressure calibrator or calibration system. A range of hand held pressure generators / pumps were thus developed which following the company's continual improvement policy have become the most recognized and efficient pressure pumps available.