This detailed sterling silver tie clasp features a moving slide rule with A and D scales on the stationary piece and a C scale on the slide. Note that the clear plastic cursor with red line is still present in its sliding frame -- a part that is missing from most clasps of this type that have been available in recent years.
The tie clip was made around 1965, as estimated by the Smithsonian Institute, which has an identical piece in the collection of the National Museum of American History. The donor of that one stated that it came from the Edmund Scientific Company.
This piece is in excellent vintage condition with minor signs of prior use as shown in the photos. Its previous owner clearly
treated it with care. There is one small section of significant tarnish on the top edge under the cursor, which
must not have been moved for cleaning and polishing. I removed just
enough of that tarnish to allow the cursor to move freely, leaving the
choice of whether or not to remove it completely to the purchaser. The top edge of the clasp is pictured both with the tarnished section revealed and with it covered by the cursor frame.
2" wide x 3/8" high.