A load cell is a transducer which converts a value of force into a proportional electrical signal. Load cells are critical elements of universal testing systems. All Instron load cells are individually temperature-compensated and tested for accuracy and repeatability on a calibration apparatus that is traceable to international standards, with a measurement of uncertainty that does not exceed one-third of the permissible error of the load cell. Instron's Massachusetts headquarters houses the largest commercial deadweight stack in the United States, which allows Instron load cells to often exceed the level of accuracy required by most materials testing standards.