Abstract: A lock, such as a mortise lock, for a door. The lock comprises a locking cylinder that can be inserted into a door leaf and a shaft having two sections, each section of the shaft having a handle at the end, preferably a rotary knob or a standard door handle and being actively interconnected by a coupling after recognition of an authorisation code. The lock can be used for various applications as a result of its construction design, with a standard locking cylinder in various doors and that it allows, a simple, reliable, low-energy actuation of the locking mechanism. To achieve this, the coupling (11) comprises at least two, preferably four or more rolling members (17) that are guided in recesses (18) of a second part (10) of a first section (5) of the shaft (3).