MDSR-4 Surface Mount Reed Switch, Low Power. This surface-mount reed switches can switch 200 V dc at 10 W. It has a low electrical footprint and require zero operating power to close the contacts. It is hermetically sealed and with magnetically operated contacts it is highly resilient to contamination. Even operating in conditions long after optical and other technology reed switches would have failed. It has Form A (SPST normally open) contacts. The glass envelope measures 15.24 x 2.28 mm and this item has an AT 22-38 sensitivity rating. Features. Surface mounting normally open switch Capable of switching 200 V dc or 0.5 A at up to 10 W Low, stable contact resistance Operating temperature range: -40°C to +125°C