# Trip force of a Keypad Dome

I am trying to understand the meaning of 'Trip force' of keypad dome on these pages, and this, and this.

Example: Trip Force: 14.1 oz. [400g]

Does it mean that when I put a mass of 400g on this dome then it will be depressed?

On another website this parameter has a different name 'operating force' and is given in units of gram-force (gf).

Does these 2 websites show same parameter with different names and units or these are different?

As you gradually push down on the dome, increasing the force that you apply, the switch will begin to displace - at a certain point, $$F_{MAX}$$, the dome will 'pop' inside out - it is bi-stable, and this is what causes the 'click' and tactile feedback that you feel. After this snap, it takes a lower force to hold the switch down that it took to push it down in the first place.
The 'reverse snap', when the switch pops back to its original shape happens when you remove force from the switch, and reach as low as $$F_{RMIN}$$.
To answer your question directly, the "Trip Force" will correspond to $$F_{MAX}$$ on this plot, and any sites that only list the force with units of grammes (a unit of mass, not force), will mean $$\text{gf}$$. This is simply a typo/error/simplification on their part.