How to check?

I have an external WD. For some reason, I don’t think it’s only 32gb (or 40gb). But that’s the size it’ll reformat to now. Is there a way I can check the capacity using P/N or S/N??

P/N: WDBAAR1200ABK-00

From the P/N; I figured it would be 120gb, is it not?

Thanks!

James P from WDC helped me with this issue. It was an unallocated partition.