The earliest Leica prototypes were developed by the company Ernst Leitz GmbH during the first years of the 20th century, but marketing did not commence until the mid 1920s. The Leicas were innovative, by orienting the image frame sideways for the 35 mm film as opposed to the cine-camera tradition of across the film-strip. The cameras were compact with collapsible lenses, for hiking and biking. The rangefinder feature was added with the Leica II during 1932, and that year both rangefinder and viewfinder cameras became available with interchangeable lenses. In 1933 the Leica III offered slow-speed shutter controls and a fast 1/1000 s shutter speed, and various iterations of the III (a,b,c,d,f,&g) series became the flagship models and best sellers into the late 1950s. Further iterations of the models I and II were offered, but did not sell well.