The Particle SIM card is advertised as 2G/3G. I was under the impression that the only remaining US carrier that was supporting 2G (ATT) stopped doing so at the end of 2016. True? Can you direct me to your page where I can review and/or purchase one of your SIM cards? Thanks.
In the US, Particle partners with AT&T and T-Mobile. T-Mobile announced that it will continue to support its nationwide 2G network through 2020, so 2G Electrons continue to work in the US on T-Mobile with the Particle SIM.
I do not believe that AT&T has yet completely shutdown their 2G network but they are proceeding to do so and 2G coverage on AT&T is becoming spotty.
EDIT: To answer your other question, the SIM card comes with an Electron.