These are made of a reed switch with contacts protected by a glass bulb which contains inert glasses, this way mechanical and electrical deterioration are kept at minimum level. This is all contained in a plastic or metallic housing filled in with epoxidic resin which guarantees protection against humidity, vibrations and shocks.
Available in the cylindrical and rectangular housing with open and changeover contacts.
Magnets of various shapes and sizes are also available to activate these sensors.