The rule is an ordinary model 1441 in a special box marked "Mini-Versal." It was used for a short time about 1971. Stephen Kay, Solon OH, sent me pictures of a Teledyne-Post box marked "1441-3 Mini-Versal" (I've lost that picture.) "Mini-Versal" is analogous to the "Universal" name for 10-inch model 1452W. Stephen's rule had no date code but the new "Teledyne-Post" company name puts it about 1972 or later and the old "1441" model number puts it about 1971 or earlier. The overlap is late 1971 to early 1972.
"Mini-Versal" appeared on boxes only--maybe in a catalog, too, but I
don't have one. No actual slide rule ever bore that name.