Sanwa snap in question.

I have been looking at some new buttons for my fight stick. And took a look at the Sanwa snap in stuff. It says they fit in a panel of approximately 2-4mm thick.

I have used snap in products before, and they all have a sweet spot, where the flaps on the back are perfectly extended and holding the clip in place. So I am confused as to how the snap in buttons can fit in a panel with such a variance. The images of the buttons look like they have a stepped lip that will clip to different sizes, but if that's the case how can they be as stable in a thicker panel as they are in a thinner panel. Since the harder the clips are pressed out the better they hold.

And to anybody that has used them in panels of different thicknesses, what thickness did you find to be the best.
I have a TE1 that I am going to be putting a new panel on and need to make sure i get the right thickness.

I would like to go with the screw in stuff. Because its safer taking them in and out as i change colour schemes. But they have less variety in the colours and the blue and yellow in particular aren't as nice.

Thanks guys.