Introduced in the late 1960’s the Heuer Autavia “30 Dato” was the firm’s first Autavia to feature a date. Although many would say an additional date function was not a vast advancement, though aesthetically the design and layout of the dial was the most discerning factor of the addition. With the case size readjusted from 38mm to 40mm, another additional feature was that it incorporated a snap-back compressor caseback which allowed the case to be controlled by the water pressure and the gasket would tighten or loosen accordingly.