Template:Infobox former monarchy 

Hi, Thumperward. The reason I reverted your edit is because there are dozens of articles using the template which do not have a specific value for the CoA width parameter, based on the assumption that the default width was 120px. When you removed this default width value, many templates suddenly found themselves with HUGE coats of arms, which were visually striking and quite ugly. Therefore, I believe the default width of 120px should be kept. If you wish to remove it entirely, then you should first ensure that all the articles using the template have a specific value for the width parameter. Regards.