Lot arrived with no issues.
I didn't pay much attention to this description at the time.

"Large group of 100+ used envelopes (completely fill a medium priority size box), from U532 to U677 with a few earlier mixed in. Lots of watermarks and variety identified by UPSS numbers. There is almost no duplication in this lot as there are plain, window, and all different watermarks on these. Many of these are from Ben Hedding and Allen Mintz, both former UPSS members. The used stationery is harder to find in many cases and many catalog higher than mint copies. "
Final count in the box was 581. $34.68 (with tax and shipping} So ~6˘ ea. !!
A modern US Stamped Stationary collectors dream.
Will post some in the appropriate forum.
pat