This vintage sliding paper chart from Waldenbooks is a unique and useful item for those interested in engineering and measurement conversions. Made in the United States in 1971, it features conversions from U.S. to metric units and is perfect for collectors and enthusiasts alike.

With a focus on science and medicine, this item falls under the categories of collectibles and engineering. The unique aspect of this item is its sliding mechanism, making it a fun and interactive tool for anyone interested in measurement conversions. Add this Waldenbooks chart to your collection or use it for practical purposes, either way, it is a fascinating item to own.