Abstract: A solenoid is provided having a simplified construction which gives precise, uniform and reliable performance. The solenoid includes a base member which supports a bobbin. The bobbin is a one-piece, integrally molded unit with a hexagonal bore that extends through its entire length and a resilient retainer or catch that extends over and partially closes the bore at one end of the bobbin but flexes to admit a plunger. The catch and a plug in the bore at the opposite end of the bobbin confine the plunger between predetermined limits. The plunger has a hexagonal cross section sized to fit closely into the bore, allowing sliding movement of the plunger in the bore and preventing rotation of the plunger. The bobbin supports a coil that produces the magnetic flux to move the plunger longitudinally in the bore of the bobbin.