The 59HS18-03-1-20N-C is a Series 59 multi-deck rotary switch manufactured by Grayhill, designed for military and industrial applications requiring reliable switching with multiple contact positions. This switch features a 1.125" diameter body with an 18° angle of throw, fixed stops, and soldier lug terminals, making it the smallest diameter rotary switch available with this number of positions and current capacity. The switch is military qualified to MIL-DTL-3786/36 and incorporates a gold-plated contact system compatible with logic circuitry, ensuring superior performance in demanding environments. It operates at 30 VDC with resistive and inductive load capabilities, supporting up to 10,000 cycles of rotational life at 250 milliamperes with resistive loads. The switch is mounted via a 3/8-32 UNEF-2A thread and includes integral assembly hardware with a non-turn washer and internal tooth lockwasher. Common applications include aerospace, defense, telecommunications, and instrumentation systems where reliable multi-position switching and long operational life are critical requirements.