The Vintage Slide Rule Keuffel & Esser K&E Beginner's 4058W Ruler is a classic engineering tool from the United States, dating back to the 1930s. This slide rule, designed by Keuffel & Esser (K&E), is a beginner's model perfect for those learning engineering principles. The ruler comes with a protective case, making it easy to store and transport. This collectible piece of science and medicine history is a must-have for anyone interested in vintage tools and engineering artifacts.