The Dornier Do 23 was a German medium bomber of the 1930s.
Dornier Do 23
A medium bomber is a military bomber aircraft designed to operate with medium-sized bombloads over medium range distances; the name serves to distinguish this type from larger heavy bombers and smaller light bombers. Mediums generally carried about two tons of bombs, compared to light bombers that carried one ton, and heavies that carried four or more.
The USAAF B-25B Mitchell, a medium bomber.
Polish PZL.37 Łoś, a medium bomber.
The Japanese Mitsubishi G4M "Betty", a medium bomber.