In 1948 together with ETA with their brilliant chief engineer Heinrich Stamm Eterna developed and launched a fully oscillating bi-directional autowinder (Eterna calibre:1194). Unlike other earlier oscillating weight designs from Rolex and Felsa the Eterna oscillating weight was mounted to a ball bearing and coupled to a clever reverser wheel system that allowed for smooth manual winding and efficient autowinding.
By 1949 the larger Eterna calibre: 1237 series was manufactured specifically for mens watches and came in several size variants, both with and without date complication. This elegant automatic movement hit the watch world like a sledgehammer; whereas the bumper automatics where loud and clanky, this autowinder was smooth as silk and quiet.
Click on the link below to see the movement review