In 1846, watchmaker Johannes Hengstler opened a small clock-making workshop in Aldingen, southern Germany. In 1920, he introduced the world’s first counter with a zero-reset function. In 1957, he launched the famous “400” electromechanical counter, made of plastic. Over the years, it evolved into a manufacturing company producing industrial counters, rotary encoders, and relays. Here, we see a six-digit “400” series counter. In Greece, it was used by OTE to measure telephone call units at telephone exchanges.