These cards are very economical, and while they might be fine for some uses, they are not suitable for mine. First, they are not 3 inches tall. Instead they are undersized by a full 1/8 inch, so they will not match up with other cards already in use. They are very lightweight and flimsy which means they won't hold up well with frequent use, and anything printed on one side easily shows through to the other side. The surface is rough and doesn't take toner well. I will be returning them and getting cards elsewhere.
I really prefer to use un ruled index cards. After I ordered several items online I found the cards were unavailable at that time for store pickup. To my pleasant surprise they were shipped to me at no extra cost. Way to go!