This vintage cylindrical slide rule calculator model "K" by Otis King is a must-have for any collector of scientific instruments. Made in England in the 1950s, this calculator is perfect for those interested in the history of scientific technology. It is ideal for calculating complex equations and displays its results in a unique and efficient manner. This item falls under the categories of collectibles and science & medicine, specifically in the sub-type of calculators and scientific instruments. Its period of use is from 1940-60, making it a rare find for those interested in vintage science equipment.