An elevator including a cage configured to ascend and descend along a guide rail in an elevator shaft, a drive unit configured to move the cage up and down, and an emergency stop device configured to urgently stop the cage when the cage descends at an extraordinary speed. The prosthesis can be elastically deformed to reduce its diameter through axial elongation. The sending device is configured to encode less than all of a device ID identifying the sending device in a packet before sending the packet on the network. A key positionable relative to the helical track and responsive to movement of the helix sleeve in a first rotational direction, wherein the key prevents further movement of the helix sleeve in the first rotational direction after a selected number of plugs pass through the plug counter.