Magnetic recorders of the disk and tape type often employ recording techniques which require contact between a transducer and relatively moving magnetic storage media. Such contact results in the accumulation of debris on the transducer which can degrade the recording and reproducing operation. Accordingly, it has been the practice to insert cleaning cartridges into such disk and tape recorders. It is shown that the external configuration of a cartridge can be used to distinguish between cartridges containing a data recording medium and a cleaning medium.