Just got this rare beauty back from service - a Porsche Design by IWC Moonphase ref 3742 These were made around 1990-1995. They are 36mm in size and very thin - about 8mm. Unusually for this era, they have an all titanium case and bracelet. They have a very interesting, high grade mechanical-quartz hybrid movement borrowed from a sister company - the JLC 630. Apparently the world’s first true mecaquartz, making it a meaningful stop on the horological journey of mankind... Some more info: _____ For the first real meca, though, you need to look to Jaeger LeCoultre and their 630 and 631 calibers. Introduced towards the end of the 1980s, these were impressively thin (half the depth of a Valjoux 7750) and, with the crystal oscillating at 32,768Hz, splendidly accurate, gaining or losing just a second or so per month. And if your watch-related OCD is particularly bad, the 630 series were all adjustable via a small screw on the backplate of the movement. These weren’t utility engines either. JLC went to the trouble of rhodium plating the movements and finishing them with côtes de Genève. They found their way into IWCs—running Flieger watches as well as the Ingenieur and the Porsche Design series. JLC used them widely too, later adding a moon-phase complication as well as an alarm function.