I still could not see a degree of filling

The inscription on the back of the package first appears quite plausible.
Once the indicator is provided as mounted on the bottle, happened first time nothing.
I weighed and found that about 2 kg of gas was still present, the gas cylinder.
After further gas consumption I mean to be able to detect a slight shift of the color values, but a unique level determination was therefore not possible.
I'll use a spring balance again in the future, so it is 100% sure how much gas is still present