On June 22nd, 2021, Rolex was awarded a United States patent on the pictured inventio: an redesigned spring for watch movement.
Springs can be a pain in watchmaking. They take up a lot of space in the movement, they are difficult to install, and often fragile. Not to mention that they tend to fly across the room when mishandled.
So, Rolex proposed an interesting solution in their December, 2016 patent application. The picture above shows the basic idea. It's an arbor with a spring around it. The spring has stops against a housing around the arbor, and can either be pre-stressed or not. So, when a rotational force is applied to the arbor (15) or a wheel attached to the arbor (12, 12'), it will tighten or loosen the spring (depending on pre-stress).
In the picture above, the spring would be attached to the arbor (25). In this case the yoke spring, which is normally a large piece, instead takes up a small amount of space where the arbor of the yoke would be anyway. This eases installation and repair, though increases manufacturing costs – which are not traditionally a big concern for Rolex.