Video translation by: @YanGunFissure (Thanks a lot!)
The route Nit de Bruixes (9a+) is famous for its numerous one-finger pockets, and successfully climbing it requires exceptional finger strength.
Note: The climbing route 9a+ (5.15) is the highest difficulty grade in rock climbing to date. Nit de Bruixes (Witch's Night) is one of the hardest sport climbing routes in the world.