The cermet trimming potentiometer is a miniature light-weight control having an extremely rugged construction. The nature of the resistive element provides an inherent freedom from catastrophic failure and offers a wide range of possible ohmic values. The design and its influence on some of the more fundamental properties of this control is discussed. The effects of both electrical and environmental stresses liab1e to be imposed in practice are given in some detail. This form of control is shown to have a number of advantages over the more conventional wirewound device, some of which can play an important role in present-day high-speed, high-reliability electronic circuits.