They both can go at first class letter rate, depending on how much stuff you put in them (no more than 1/4" thick).
Thanks Michael, i paid like 3 dollars for about a hundred...so i should not be purchasing the 6x9 guys for a while.
Decades ago, we bought these by the thousands so that we could send 8.5 x 11 documents with #10 BRMs. Still available !!! https://okpaper.com/toolbox/envelope-guide #12 ... 4.75" x 11" #14 ... 5" x 11.5" Cheers, /s/ ikeyPikey
I love to recycle..find them at yardsales instead of paying 20 cents apiece at Staples !