They hold ~150 modern and silver-age comics, including bags and boards

I've filled one up and it holds and supports the comics just fine.

Plus the slight gap at front and rear bottom inside can catch a loose comic if you're not careful

I don't really have any valuable comics, and a lot of them are in bad condition to begin with, so I don't care all that much.

When you finally get the boxes together, there is a significant amount of open space at two of the corners - enough to be concerned about their ability to be moved/protect your comics