These pens have two buttons which is typical for an EMR pen.
I tested four PW550 series pens on 2024/08/30
1x PW500S
4x PW550
I'm not good at measuring IAF but each seemed to be around 3gf.
PW550 - 223.6gf
PW550 - 560.0gf
PW550 - 850.0gf
PW500S - 735.5gf
As is typical for EMR pens, these pens have a response that bows up. All 4 hit 50% at around 100gf.
So as I often recommend, you should consider a pressure curve to linearize this response so that you have more pressure control at the lower end of the physical pressure range.