The company first produced round and shaped watches for the American market with their own shaped small seconds movements. By 1931, Zila was producing a rectangular 4.75 ligne movement with small seconds as well as a large 10.5 ligne 8-day movement. A smaller 6.75 ligne 8-day movement was added by 1932. A 8/75×12 ligne movement was added by 1934. By 1947, Zila offered a range of wristwatches and pocket watches and also supplied movements to other companies.
By 1954, Zila (now called Zila Watch Co. Ltd.) added the Hislon and Irocal brands. The company also offered an alarm watch known as Belltone and waterproof watches called Watermaster. The new slogan was “reliable Swiss quality watches.”