The open frame linear solenoid is the simplest linear solenoid design. It uses an open metal frame, a taped or overmoulded coil, and a movable plunger in the centre of the coil. Open frame solenoids are more cost effective than other linear solenoid types, and are typically selected for applications in which extremely long life and precise positioning are not so critical. Open frame solenoids are available in two frame styles: the C Frame [or U Frame] style, in which the coil is enclosed on one side; and the D Frame [or Box Frame] style where the coil is enclosed on two sides. Open frame linear solenoids are generally secured by mounting screws through a panel in the application and threaded into the solenoid’s frame.