Some tachymeter/telemeter/pulsometer watches featured spiral-design “snailed” scales around the dial. To the Chronoscope, Omega opted for a far more symmetrical look that features a couple concentric circles that come with the crucial scale info when also not materially distracting from Main dial legibility. Such as the ref. 6536 higher than, https://www.watchesworld.com/frozen-in-time-luxury-watches-for-winter/