Advice on 24V Multiplus

I am looking at an ad for a 24V Multiplus II on Carbonite.

With 2 200Ah lithium batteries, R20000

But the picture seems to be of a Multiplus not a Multiplus II, and the seller ‘thinks’ the inverter is 8 to 12 months old.

What is the history of Multiplus and Multiplus II,
when did the model names change, and can one tell the age of an inverter from serial number, or firmware.

What questions should a buyer ask, and when should one walk away?

The seller can just look at the serial number. It will start with HQ, followed by 4 digits, the first two is the year, and the next two is the week of the year when the unit was manufactured.

You can still get the aluminium case models, they are still on the website. There are also smaller plastic-cased units that are also properly called a Multiplus (not a Multiplus-II).

Best is to ask for the serial number, or at least the first 4 digits. That will remove all doubt.