Basic White 9x12 envelopes which I use to send my clients copies of their tax returns. I use these and the 10x13. I started using the white as opposed to the manila I like these better. I found that the ones you just peel the tab and stick did not make me feel as secure since I am generally mailing confidential information. I like the ones that have the glue but you have to wet to activate they seem to stick better. I think the White looks more professional and the post office told me that the manila with the metal tab they charge more to mail because sometimes it cannot go through the automated machine. So another reason I like the white no metal tabs.
When selecting this product I was looking for this size and didn't need a clasp. All the manila-colored ones had a clasp and were more expensive. (I think the manila ones are also made with a heavier weight paper but I only realize that in hindsight.) I chose these because I didn't really care what color the envelopes were I just needed this size and these were not as expensive as the others. WHAT I DIDN'T THINK OF is that since they are white and made of a thinner paper than the manila ones (which again I did not realize until after purchasing and using) THEY ARE SOMEWHAT SEE-THROUGH. Therefore they are not the best option for sending tax documents (which is why I purchased them). I ended up adding sheets of blank paper on either side of the materials I was mailing to add privacy. The envelopes are fine but I just didn't think of the privacy factor again since I didn't realize that they are not just a different color but a thinner paper altogether (as compared to the manila ones). Lesson learned; hopefully my experience/comment will help someone else choose the right product!
When I am doing a mailing from my home for my employer I need it to look every bit as professional as neat as if it were printed at the office. These envelopes give me that result.