The dry reed tube is a magnetic control passive switching element, which does not need power supply and relies on the magnetic field to drive the internal reed to close/open. The shell is a sealed glass tube, which is filled with inert gas (nitrogen) or vacuum. The contact is not subject to air oxidation and water vapor corrosion. Structural composition Glass shell: sealed to isolate water vapor and dust Two magnetic reeds (iron-nickel alloy): one end is overlapped to form a contact, and the other end leads out a pin Internal medium: high-purity nitrogen/vacuum to suppress arc and prevent contact oxidation Contact coating: rhodium, ruthenium, gold, reduce contact resistance, improve service life