The model 330-H-10SEC Operate Delay Timer is a DPDT potentiometer (knob-adjust) timer designed for a wide range of industrial applications. Examples include automatic and machine tool control circuits, HVAC circuits, and warm-up delay circuits. Solid-state timing circuits in each model drive an internal electromechanical relay. This model is functionally interchangeable. It is UL Recognized and CSA Certified.