The Swiss precision of the Ronda 712 quartz movement, lubricated with oil bath. Stainless steel AISI 316L. with subsequent PVD treatment, completely filled with a special oil that emphasizes the dial, creating the illusion of the absence of glass, and an optical effect of a more intense black and higher legibility. Visible air bubble on the dial to compensate the temperature variations. Distinguishing crown on left side. Diameter 44,80 mm.