that page horn is funny!
Be sure to measure the entire protective sleeve carefully. The packaging may say 12" x 12" but the actual size of the page does vary between manufacturers. And measure the width of the area with the holes. This too can vary (by a lot). There is nothing worse than buying sheets to find out they are much larger (or smaller) than you are currently using (or poke out of your album). I have found it best to commit to one brand for each album. But this can be tough finding certain brands. Even the most popular brands can be difficult to locate. When I am buying sheets I always buy extras.
And, sadly, these protective sheets DO scuff up, get dog eared, get creases, etc. The more the albums get viewed, the quicker the process. I have just come to accept that occasionally I have to replace protective sheets. Think of it this way…it’s a good thing the protective sheet are taking the “wear & tear” and NOT your actual page. I hold on to my scuffed protective sheets and reuse them for kits or storage.