These gummed envelopes for laser forms work perfectly with both the excel program invoices and with the quick book invoices. They're also large enough that a return envelope (Size 9) can be included without having to fold it. I have used similar envelopes in the past and find that these are more flexible and the internal folds to not "catch" on the contents when one tries to enclose invoices. The only improvement I would recommend would be if there were an easy close version that had a self-sealing flap.
We use the Staples Double-Window Gummed envelopes because of the value and durability of the product. We have changed all our invoicing purchase orders and other letters to match the envelopes because of their durability and value for the low cost. It makes sense from a cost standpoint to use one simple product for all situations which means we stock fewer items and that equals lower costs. Simple use means more profit in our company which is a win for all. Small savings from expendable items spell success.
When you want a good product at an efficient price point this is the one to go with. Great for everyday use. Priced for the small community group that need to keep pricing in mind when using everyday products. This works perfectly for us.