I have no idea what the internals are like. I only know what they meter out at on the provari. The one I am using right now is supposed to be 1.7 ohms. I metered it when I first started using it and it said 2.0, now, a day later it is up to 2.4. This isn't usual, they usually stay around 1.7-1.8. But the last 3 I've used have done this. I don't blame the vendor though, he doesn't make them, he just gets them in bulk like every other vendor does and sells them. I don't really mind them changing resistance, I just up my voltage.
This starts to become a problem for someone using a 3.7 device and doesn't have a multimeter. I was using the first carto (that did this) on a vv box mod and noticed that the vape was getting weak.

I couldn't wait to get home and see what was really going on. It metered at 2.4! no wonder the vape was weak to me since I was thinking it was 1.7. So someone who may be newer at this and doesn't know what's going on would be freaking out wondering if it was the carto or the device. I do have a multimeter but it only tells me a round-about reading, I never really knew an accurate reading.
so instead of tossing this carto, I can still use it and get a good vape.