The reed switch is hermetically sealed. Electromechanical and semiconductor sensors are not hermetically sealed. In many of the window washer sensing requirements, manufacturers are choosing a turnkey reed sensor. This means that the reed sensor incorporates a sensing float that rides with the rise and fall of the liquid. It has an embedded magnet that will activate the reed sensor once the float comes within sensing distance of the hermetically sealed reed switch. The reed switch will in turn activate an indicator light and also supply a signal to the on-board computer. The hermetically sealed reed switch can also switch power as well as very low level digital signals directly. Electromechanical and solid state sensing technologies cannot carry out both functions directly. They will need additional components, which add more cost.