The Ronda 021P-21 watch movement, introduced around 1955, featured several specific modifications by Wyler. These include the Kif-Duofix combined setting for the escapement wheel, Wyler-Incaflex shock protection with elastical spiral balance spokes, a disc-shaped lever bridge and nose at the train bridge to limit the spring travel of the balance, and a crown wheel bearing secured with three screws instead of one center screw. In terms of functions, the movement provided manual winding and a sweep second hand.