Thanx and I just found a previous post here regarding the movement. Next question: I this on a redial?
That is a redial. Zenith's 156 is Universal Geneve/Martel's 285 - one and the same. Before acquiring Martel in 1960, Zenith had no in-house chronograph, relying on Martel and Excelsior Park to provide the machinery - both good manufacturers. Once UG let Martel go, Zenith bought it to bring chronograph expertise in house. We all know how that evolved!
Here's one authentic dial for reference. There are multiple dials of course, but this should give you an idea what the redialer was shooting for