This vintage slide rule from I.R. (International Rectifier) is a must-have for collectors of electronics from the 1960s. Made in 1964, this silicon zener voltage and shunt regulator slide rule is a rare find. The cardboard paper material and U.S.A. printing make it a durable and valuable addition to any collection. The slide rule is perfect for calculating shunt and selector voltage regulators, and is a great aid for students and engineers alike. Its precise calculations and easy-to-use design make it a valuable tool for anyone interested in vintage electronics. Add this unique piece to your collection today. Pre-owned in good condition Please see pictures of actual item to be shipped