Tissot Visodate (roulette)

This watch stands out among 60 years+ old vintage watches (it dates from ca 1959). The dial is so clean! Fully serviced, with 12 months warranty, the high quality Tissot caliber 27B-621 is numbered 4340523, and the 33,5mm stainless steel case has reference number 57018-1. What “roulette” means? : The even dates are in red, the odd ones are in black 🙂