The product is a Vintage 1947 Keuffel & Esser Slide Rule Model # 4092-3, manufactured in the United States. This collectible item falls under the category of Science & Medicine (1930-Now) and specifically in the Engineering field. The slide rule is a rare and classic piece of equipment that was commonly used for calculations in various industries before the advent of electronic calculators. Made by a reputable company in the USA, this slide rule embodies a piece of American engineering history.