Triple calendar.
JLC has been making these since the 1940s. It was a classic style/type of watch manufactured by many companies back then—very much an “every man’s” business watch—that ultimately fell out of favour with the public post World War II along with small seconds sub dials. Interesting to see that they’re sort of coming back now (via VC, Tiffany’s, maybe others). JLC is the real deal, though, having manufactured them when essentially no one else did.