Aircraft fuel extractor - GIF

Aircraft fuel extractor.

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Previously:

https://www.homemadetools.net/forum/...282#post130965
https://www.homemadetools.net/forum/...8001#post86610
https://www.homemadetools.net/forum/...3179#post77586
https://www.homemadetools.net/forum/...129#post149617
https://www.homemadetools.net/forum/...543#post136044

how? how is it extracting the fuel?, why the twist move partway through the process?

I used to go flying with a friend in his Cessna 172, he would always use a bottle like this to pull gas samples out of both wings to check for water in the tanks. Rather important not to have any....