The invention relates to a power unit which is receivable in or at a medical handheld medical device in a disengageable manner, wherein the power unit includes at least a voltage source, a motor and/or a circuit board, wherein the power unit includes an arrangement for identifying which is configured to identify at least one feature of the medical handheld device and to emit a signal caused by the identified feature or based on the identified feature. The invention furthermore relates to a medical handheld device, comprising at least one power unit according to one of the preceding claims and/or at least one feature which is provided to be identified through the identification arrangement. The invention furthermore relates to an arrangement for identifying a medical handheld device that is connected with the power unit according to the invention.