For your consideration, here is a 1963 Glidden Gallonage Sliding Calculator Computer. It measures 3 1/4 by 8 1/2 inches. It has a little wear on it and a small crease on the outside of the fastener in one corner. Item pictured is the actual item up for sale and comes from a non-smoking household. (74.830r-.3ob)
[Thanks for looking!]