A lock having a body, an engaging element having a first end, a locking mechanism for securing the first end to the body, the locking mechanism adapted to selectively conceal or reveal a passage in the body, through translation of a sliding gate, through which the first end may move to unlock the lock; the engaging element has a second end which is retained by the body at all times but is free to rotate. In other aspects, a lock has a body, a shackle having heel and toe portions, the heel portion engaged within the body, and a gate mechanism for selectively concealing or revealing a passage in the body from which the toe portion may move to unlock the lock, wherein movement of the toe portion is achieved through rotation of the toe about the heel.