A lock includes a housing, a shackle, a controlling unit and a lock core. The shackle has a root section and a free section. The root section is disposed in the housing. The free section extends from the root section and is disposed outside the housing. The controlling unit is disposed in the housing and connected to the root section of the shackle. In particular, the controlling unit is capable of rotating about the root section and axially moving with the root section. Additionally, the lock core is disposed in the housing and is configured to control rotation of the controlling unit.