Mystery meat 2- and 3-pin soft starter modules

[5U4GB]

I've got some gear like table saws and planers where I'd like to reduce both the kick and inrush current, and the obvious solution is one of the vast number of mystery-meat 2- and 3-pin soft starters available from places like Aliexpress and eBay, things like this.  In particular one of the items, a mitre saw, has close to zero space to fit anything so even the smaller 2-pin device is going to be a challenge to install.

Does anyone know what the difference is between the 2- and 3-pin devices?  Given the tiny size I assume there's not much more than a thermistor in there, but why 2 vs. 3 pins, and is there any inherent drawback to the 2-pin form?

[Jeroen3]

I suspect these are all thyristor dimmer based soft starters. A two wire one will never be 100% on because it needs to shunt a small bit of current during off-time for it's own supply.

Or the two wire is just a passive ptc.

[5U4GB]

Or the two wire is just a passive ptc.

That's what I suspect for those ones since they're something like 30x20mm which doesn't leave room for much but a thermistor.  Which would unfortunately make them useless for a mitre saw because that'll typically be used for repeated cuts with little to no time to cool off between cuts.