Avenir Excursion Bicycle Panniers

I’ve been looking on other sites, but can’t seem to find the dimensions of the two bags - need to know if it will fit my laptop. Also - How do these bags attach to the rear rack – clips? straps? can you separate the two bags? Thanks!

I went to Amazon, searched “Avenir Excursion Bicycle Panniers” and then selected the smaller of the two sizes.

According to some of the questions on the site, there’s a bolt/hook system of attachment.