These are really great. The zipper works well and will stay on if you keep your finger held down as you push the closure along the edge. They are made of thick, smooth plastic and they are sturdy. They are pretty sheer, I usually like more opaque plastic envelopes but I can always put a piece of paper on each side so the contents can't be seen. They do expand a bit as well. I purchased the yellow and it's a very bright lovely yellow color.
✔ I recommend this product