I started using these mailers several years ago. There is nothing available anywhere like these! They are so easy to use. There is a strong piece of adhesive tape to seal these boxes, so it isn't necessary to invest in more tape or bubblewrap, etc. Postal workers always ask me about these boxes because they are so exceptional. If you look at the picture of this mailer, you will see the added reinforcement on the sides. It is very sturdy and helps protect the books as they travel through the system. I mail 8 1/2 x 11" books in these.
I am so happy that there is a new ColumPac distributor in the US! I ordered these boxes over the weekend and they were shipped first thing on Monday. I received them 2 days later. (I am also on the East Coast.)
I had excellent feedback from the owner of this company, too.
A HAPPY CUSTOMER!