I think what it means is that you get the lower limit as a 'free', regular checked bag (maximum). Over that, it is an 'outsize item' and for that, 190 is the maximum. Beyond that, you're in cargo territory. The outsize label is often applied to skis, golf clubs, etc. I guess you'll be fine - your box will get spat out of the oversize baggage belt at your destination, as it were.