The #10 Airmail Envelopes would be suitable for sending important documents, like critical paperwork, via US mail.
#10 Airmail Envelopes - 4 1/8 X 9 1/2 - White - 50/Pack
10 x 7" STRONG BROWN RECORD MAILERS / ENVELOPES FREE P+P - NEW
#11 Envelopes - 4 1/2 x 10 3/8 - Brown Kraft Manila - 50/Pack
JAM PAPER #11 Envelopes - 4 1/2 X 10 3/8 - Brown Kraft Manila - 50/Pack
#11 Envelopes - 4 1/2 X 10 3/8 - Brown Kraft Manila - 50/Pack
