The ET21SD1CBE is a sealed subminiature double-pole (DP) toggle switch with on-none-on switching function, manufactured by C&K Components. It features a sealed design that protects against solder and cleaning process contaminants, making it suitable for harsh environments. The switch offers a contact rating of 0.4 VA maximum at 20 V AC or DC, with contact resistance below 20 mO typical at 2–4 V DC with 100 mA, and an electrical life of 30,000 make-and-break cycles at full load. The device is available with multiple actuator heights (M at 0.240", S at 0.400", L at 0.320", S1 at 0.540"), termination options including PC thru-hole and surface mount configurations, and contact materials such as gold, silver, or gold-over-silver plating. It is RoHS compliant and commonly used in hand-held telecommunications, instrumentation, and medical equipment applications where compact size, reliability, and sealed construction are essential.