This device is like a normal Sim card, but it can enable your phone like the flagship phone with Esim capablity, with that you could enjoy cheap roaming data around the world(by installed related company's esim card, like KeepGo's data, there are many choice depends on your need and area.
Esim.me card 's offical website
https://esim.me/
There is an extra card, if you buy would cost around $51 CDN, PM me if you are interesed.