Have you ever used a book stand?

I was reading a relatively large book, not thick but tall and wide, and was struggling to be able to hold it up. It occurred to me that someone must have invented a simple portable book stand for the purpose. I did a Web search and found several similar products. The prices seemed reasonable for someone who does a lot of reading. I bought one of the cheaper ones and have been using it for about two months and have been very satisfied. One nice use for it that I had not originally thought of is for holding up cookbooks while following a recipe.

I am surprised that I had never heard of these before. Have you ever used one or seen someone using one? It folds up and fits easily into a backpack. On more than one occasion, when I was using it in Barnes & Noble, someone came up to me to ask where I got it.