The #2 padded envelop is presumably designed to protect letter-sized documents. However it is about 1/4" too narrow to make this generally feasible. It is possible to insert an 8.5 x 11 inch stack of say 10 sheets of paper but only with significant force and risk of damage to the contents. Making only slightly wider and longer and you would have a winner.
As a small publisher I use these envelopes on a daily basis to mail single books to end users. I use the post office's "media mail" for the books and the cost savings over using a box is significant! I highly recommend these envelopes to anyone shipping small quantities of items that need protection and do not want to spend a fortune on the extra weight of the box. It is also easy to use reliable and never need extra sealant to keep it closed. It is also easy to use shipping labels or in my case hand-write the addressee.