An apparatus comprises at least one RFID chip (30), which is surrounded by a metallic outer casing (11) of a packaging unit (1), is used for radio-frequency identification and has a circuit (32) and an antenna structure (31), and a transmitting/receiving unit (41) for transmitting a transmission signal (42) and/or receiving a response signal (43) from the RFID chip (30), wherein the response signal (43) can be evaluated using an evaluation unit (44) which is connected to the transmitting/receiving unit (41). The RFID chip (30) has an operating frequency in a frequency band (50) below a range of a blocking frequency (54) which is determined by the conductivity of the metallic outer casing (11) and the thickness thereof.
