Rolex was an early adopter of anti-shock devices and supported the hinged Kif Type 3 "Elastor" anti-shock for many years. In 2005, Rolex patented their own anti-shock device, and in 2008 they registered the name, Paraflex.
Paraflex functions similarly to other anti-shock devices, allowing the cap jewel over the balance pinion to move slightly in response to a shock rather than breaking. This Rolex version is recognizable thanks to its unique design: A rectangle with slightly curved ends is positioned obliquely across the jewel, connecting from the right "leg" to the left. The entire Paraflex assembly can be removed from the chaton in which it is mounted, unlike the Kif devices used previously.
The first movement to be equipped with Paraflex was Cal. 3186, featured in the limited-edition anniversary-model GMT-Master II, Ref. 116718LN in 2005. It was since added to many movements that descended from this, including Cal. 3132, 3136, 3156, and 3187. It is a standard feature on the new Chronergy movements as well.