For context: Lamy is a pen manufacturer. The things in the picture are a Lamy fountain pen cartridge (left), and the Lamy Z24 fountain pen converter (right).
The cartridge holds more ink than the converter, but its plastic is very thick and if I need to prime the feed during writing I have to break fingers trying to squeeze that ridiculously thick plastic.
In alternative, the converter's piston is so hard to rotate that I need to arm myself with the patience of a saint and twist the bloody little thing with unusual force but without moving the pen, unless I want to have the bottle of ink toppling down on me.
Lamy, for goodness' sake, how is anybody supposed to use this thing and not hurl a bunch of expletives to you?