Cassette (70) for a medical instrument (100) including at least one tray (1), the tray (1) having at least one holding means (10) for retaining the medical instrument (100). The holding means (10) has at least one magnetic element (20), in order to retain the medical instrument (100) and preferably a relief structure (13) which defines a seat (14) on which the instrument (100) can be securely retained by the magnetic element (20).
