I liked the self-sealing feature for a bulk mailing but the seal did not hold and I had to add tape to secure. The documents that I mailed were heavy (100 pages) and few envelopes started to tear from the metal spiral in the document binding.
I used the pull and seal envelopes for mass returns of rebates with invoices and had to buy additional packing tape to assure envelopes didn't open. Not sticky enough (unless only have 1-2 sheets of paper in envelope).