Is this a cast iron or metal toilet flange?

Question

I'm going to use Set-Rite flange kit to bring up the height, but the instructions say to use a wax ring for cast iron or the included rubber gasket for metal. Not sure which method to use. My tubing is ABS, but the flange is metallic. Could this be a cast iron flange?

I did see a youtube video where the guy used the wax ring method even with a plastic flange, is that better than the flimsy rubber gasket?

Answer 1

The Set-Rite Flange Kit instructions I find online say to use both the foam-rubber gasket and a new wax ring (not included in the kit).

The foam rubber gasket goes down 1st onto the existing flange, then the red plastic spacer (choose the one with the appropriate height), then the yellow plastic flange extender.
Lastly, a new wax ring goes on top of the whole assembly.

So the foam-rubber gasket is only intended to seal the interface between the existing flange and the spacer/extender assembly.
The wax ring on top seals between the toilet and the flange extender, just as it would normally seal between the toilet and the original flange.

_{Extract from linked instruction sheet}