Bolta film is a variety of unperforated 35mm film with paper backing. The film advance can be controlled by a red window, so that cameras using Bolta film were simpler and cheaper than those using perforated 35mm film.
Bolta film was introduced in 1936 by the German company Bolta-Werk for its Boltavit model. The Bolta company was renamed Photavit and abandoned this special film after some time. A Japanese camera called Boltax introduced that film size in the country in the late 1930s. The Bolta-size cameras were quite popular in Japan until well into the 1950s.