Thank you. I don't know what the Ohms rating for the Cartomizer is(?) How can I find the answer, please? Nor do I know the Wattage of the Cartomizer(?)
Well, the likelihood of it being below 2.0 ohms is probably slim on such an old atomizer. That's probably why Izan used the 2.0-2.5 range.
At a 4.2 max voltage, that old atomizer would have to be 1.7 ohms to reach the 2.5 amp limit of the battery, and that 1.7 ohms is unlikely (however not impossible).
You'll need an ecigarette meter or a multimeter or a box mod to find out.
You can ask the vendor but you could have an atomizer with a defect causing the ohms to be lower than they were manufactured to be.
If it is a 510 threaded cartomizer, take it to a vape shop and they should be able to check it for you. If the cartomizer has any other thread on it they still may be able to check it for you if they have a multimeter. Threads that are not 510 have been so scarce for so long that 99% of vape shops will not have the right ecigarette meters or adapters for such devices so they would need a multimeter. Back in the day it would be probably be a good bet that a vape shop would have a multimeter on hand, but today that isn't a good bet.
But every vaper should have a way to measure things like atomizer resistance, regardless of what equipment you are vaping on.