I used to drag along a big heavy notebook with all my checklists in it when I went to card shows. Now with this site I can just pull it up on my phone or tablet and I can access any set in my collection to see what I have or don't have.
Since I found this site after COVID, I've only had 2 card shows in my area that I've been able to make but I'm sure to point anyone I see carrying notebooks or pads of paper to this site pulled up on my phone. And what sells it the most is that you would now have access to your collection any time you happen to run across any random lawnsales or flee markets selling cards when you normlly wouldn't have expected to find any.