Outer body is made of plastic with a notch on the top right corner. It incorporates a small circuitry with a flash memory chip and an onboard controller. A small mechanical sliding switch on the left side is used to lock the card. If the switch is moved to position it so as to lock the memory card the card becomes read only i.e., you cannot write or delete any data. In the lock position, the mechanical slider pushes a miniature switch inside the memory card reader. These in turn is detected by the controller of reader which disables the write and delete operations of data.