Title
http://meder.com/reed-sensor-mk21-uk.html
Description
MK21 sensors are magnetically operated Reed proximity switches designed for screw mounting. The sensor should be mounted on a fixed surface with the actuating magnet on the moving surface. Introduction or removal of the magnetic field determines the closing and opening of the Reed Switch. Leads are Teflon coated. Designed for extreme environment. High temperaturs, 150 °C, resistant to water, fuels, oils, ink and most acids.