Not unreliable and inaccurate

Assessment: Can me unfortunately the positive reviews do not connect: sometimes red, sometimes greenish, sometimes RED, GREEN times, depending on how strong and how vertical it presses the thing in the steel bottle or up and down slides. A clear and reliable indication of the transition from full / empty, I can not find anyway.
Addendum: Must revise my initial negative assessment. Have the unit now tried several times and found that it shows quite well if you pressed on the bottle it down firmly (!). One just needs to identify the transition RED / GREEN Gradually (and not by shifting).