The first full-size glass door oven was invented and manufactured here by Ernst H. Huenefeld of The Huenefeld Company in 1909. Specially designed and patented sheet metal frames in the door allowed for expansion and contraction of the glass. The large window, guaranteed against steaming up or breaking from heat, allowed users to view their baking without opening the oven door. Huenefeld had acquired this property in 1903 for a new factory. The Huenefeld Company, established in 1872 on Pearl Street, moved its manufacturing here in 1904 from its downtown Cincinnati locations. The company, in operation until its sale in 1966, was widely known as a manufacturer of ranges, stoves, ovens, heaters, furnaces, refrigerators, washing machines, and other household products. A standard feature in homes today, the glass door oven was a technological breakthrough in 1909.