The Kaehni brothers, William "Bill" L. Kaehni (1895-1950) and Francis "Frank" J. Kaehni (1897-1986) were electronics engineers, inventors, and entrepreneurs. The brothers invented radio transmitters, navigational devices for airplanes and ships, transistorized car ignitions, and heat control systems. They also built and installed public address systems. This small collection primarily consists of the Kaehni brothers' class notes from courses taken at the Case School of Applied Science (now folded into Case Western Reserve University). The notes are most likely Bill Kaehni's, but could also be Frank Kaehni's, as they are mostly undated. Of significance is a bound biography written in 1998 by David C. Barnett using documents from the Kaehni family and firsthand accounts from their sister, Marie Kaehni, who provides her own memories in the afterword.