The Stearman 4 is an American commercial biplane that was manufactured in the 1920s by Stearman Aircraft. They were marketed at the time as fast and luxurious executive transports and mail planes for about US$16,000.
Stearman 4
A Stearman 4-EM Senior Speedmail in the Canada Aviation Museum.
Stearman 4-C Junior Speedmail CF-CCH showing characteristic front manifold exhaust of the Wright J6 radial.
Stearman Model 81 photo from L'Aerophile July 1933
Stearman Aircraft Corporation was an aircraft manufacturer in Wichita, Kansas. Although the company designed a range of other aircraft, it is most known for producing the Model 75, which is commonly known simply as the "Stearman" or "Boeing Stearman".
Boeing Stearman PT-17
Stearman 4-D mailplane of 1931 in markings of Western Air Express
Boeing/Stearman N2S Kaydet at NAS Corpus Christi
Stearman XBT-17