A kit that may include a locking unit and an external portion of a motor housing; wherein the locking unit comprises a threaded opening and first securing elements; wherein the external element comprises an opening and second securing elements; wherein the threaded opening is shaped and positioned to mesh, in a coaxial manner, with a thread that is mechanically coupled to an axis of a motor; wherein the first securing elements and the second securing elements are shaped and positioned to mesh with each other and prevent a rotational movement between the first securing elements and the second securing elements.