W 121 = Cockpit-clock
W 121-II = speedometer
These two designs derive from one car model: the 190 SL, introduced in 1954 and built 1955-63. A total of 25,881 of the roadsters left the factory - and became coveted collector cars.
The sizes of the watch faces - one replicating a speedometer; the other replicating a clock - match proportionally with those of the car instruments. A perfect pair.