In 1978, Tissot created a quartz model characterised by a slim case, narrow indexes and a steel bracelet. Its wide, horizontal lug, typical of the time, was perfectly integrated into the flat tonneau-shaped case.
A few years later, Tissot registered the name PRX. “PR” stands for “precise” and “robust”. The “X” stands for the Roman numeral ten and for the pressure of 10 bar, which corresponds to a depth of 100 metres, to which the watch remains water-resistant.