This vintage KEUFFEL & ESSER slide ruler 4092-3 is a must-have for any collector of drafting tools. It comes with its original leather case, adding to its charm and authenticity. This ruler is made for those who appreciate the quality and craftsmanship of yesteryear. It is perfect for display or for use in technical drawing classes. The country of origin is unknown, but this only adds to its mystery and allure. Don't miss out on the chance to own a piece of history with this KEUFFEL & ESSER slide ruler.