I use this to mail things like pictures cds car keys and gifts that don't require a box. These are easy to seal easy to label and don't require any special services for odd-size etc. These are easy to open by cutting the edge where the flap is. Otherwise you have to be quite tough to be able to open it bare-handed (rip it apart).
You can't fit 8.5 x 11 papers inside very easily. It is too tight and they get damaged trying to cram them in! Stick with the regular Staples 8.5 x 11's.