These are good for the price. Another reviewer mentioned cutting them to width with a hack saw... My husband cut ours with a miter saw and 80 tooth blade.  Keep them rolled tightly and make sure they are rolled evenly first. 

These let in light but block the heat of the sun. They are very light weight and will blow around with even a gentle breeze. If they flap around too much I believe they will break apart.  

They don't have cords, you have to roll and fasten. I don't like the fastener which is too hard to clip and unclip when the shades are rolled up. However, they look nice and do the job they were purchased for.