This timer designed for film processing. It can time up to 50 minutes.

Time can be set by handle on the front by turning it to desire number.

Than long level on the back need to be pushed up to start timer.

When time is up alarm sound fire for about 2 sec., and you can set up timer for next step.

Body made from plastic, probably corbolid. On the back also cocking handle. This timer made on the base of popular alarm clock.

By the way it looks and how it built, timer estimated made in the end of 1950s- beginning of 1960s.