7 ea Re-Valued postal envelopes

 7 ea Re-Valued postal envelopes.  NOTE:  The Post Office has always sold Postage-Paid envelopes, primarily to Business customers.  In the 1960 and 1970s, First Class mailing rates were changing so quickly that the PO was getting stuck with old envelopes that no longer reflected current rates.  The PO would then put an additional machine-stamp on the envelope to then sell it to the public at the new rate.