What you have there is a folder containing a First Day Cover of the USA 39-cent Sperry airmail stamp given out to all the employees of Sperry Corporation as a souvenir at that time. Sperry Corporation was bought out by Burroughs Corporation and they merged under a new name, Unisys Corporation, which still has computer systems, running on MCP and OS2200, installed around the world to this day. I have 3 of them, just like yours.
Max_Power - I started with Burroughs Corporation in 1975 as a computer hardware electronics technician. After the merger, there were 35 "field engineers" as they called us, in our branch, but I saw a lot of Sperry guys have to clean out their desks. That's how I got three of these FDC folders, before they went into the trash can. I survived all the layoffs by keeping my head down, doing what I was told, and grinding everyday, retiring from Unisys in 2017. They never got me, I was the last one left of the 35.