The KSK-1A35/1 Series Reed Switch is a miniature high voltage reed switch with glass length of 10.5mm and diameter of 2.1mm. This reed switch has a rated power 10 W, Switching voltage 1,000 VDC, Switching current 0.7 Amp DC. Most used, flat leads.
High voltage, industrial, test and measurement (ATE)
https://Data Sheet Link:standexelectronics.com/products/ksk-1a351-series-reed-switch-3/