The product is a set of three slide rules, including the ACU-MATH 400, KEUFFEL & ESSER 4092-3, and DIETZGEN 1773 (mini). These vintage tools are used for engineering and mathematical calculations. The ACU-MATH 400 is a larger scale slide rule, perfect for precise measurements and calculations. The KEUFFEL & ESSER 4092-3 is a classic tool with a reputation for accuracy and reliability. The DIETZGEN 1773 (mini) is a compact and portable slide rule, ideal for on-the-go problem-solving. These slide rules are collectible items that hold historical significance in the field of engineering and mathematics.