Thin paper not index weight. Have grooves on them where lines would be - only thing it lacks is the ink sprayed lines. If you hold them to light the lines are clearly there and running a pencil lead over them shows them up. Not useful for things that need a completely smooth surface.
I waht to make some gag business cards. This was perfect for what I wanted to do. I make 4 to 6 funny business cards at a time and this qorked out perfect!
I've tried a variety of index cards lately and they have all been only slightly heavier than copy paper. Index cards anymore are just scratch paper hardly the quality of "card"
Using these 5 X 8 cards for my cartoon drawing class. Small size reduces waste and encourages experimentation. Small format allows completion of several drawings over a class period.