Wahooo - getting a lot of orders for my book Creative, Not Famous: The Small Potato Manifesto, which as luck would have it is 6"x6". The post office hits you with a surcharge for sending square envelopes first class, which may explain the deep discount on this site. No square surcharge for Media Mail, which means, if I burn through this 200, I'll order more! Mailers Direct has the best price in Internet town! Sturdy, clean, and vastly less time consuming than cutting down and taping up the pre-used Amazon Prime mailers my neighbors were donating to the cause before I wised up and placed an order with Mailers Direct.