I typically use Moleskine pocket cahiers, which are larger than these extra small notebooks.  I tried these because I wanted something smaller I could stick in my pocket.  These plastic covers would "seem" to be so much more durable than the cardboard cahiers but they are not.  The plastic cover separates from the notebook.  It's pretty ugly.  I had to use clear tape to secure all 4 corners as all were peeling badly.  Back to the cahiers for me.  I wish Moleskine would make cahiers in this extra small size.