The physical characteristics of these cards are their weight, 0.07 ounces, their size, one sixth of a credit card (32 mm x 24 mm x 2.1 mm) particularly lends them to communicating mobile markets: personal assistants/PDA, MP3 drivers, Mobile phones, also to digital equipment such as cameras and videos. Their rate of data-transfer varies between 2 and 4 MB per second. Compared to the Multi Media Card ^TM composed of 7 connexion pins, the Secure Digital ^TM card is composed of 9 connexion pins. This new organisation allows faster transfer of data while the memory card is on SD mode.

On the other hand, the Secure Digital ^TM has an integrated security mechanism, the CPRM - Content Protection for Recorder Media - which insures a high degree of protection and file-encryption. It controls the reading, copying, transfer or erase functions. In this way it becomes possible for the user to forbid or authorize the copy or to offer a reproduction right.