USB Flash Drives or commonly called as Pen Drives are popular removable storage media having a storage capacity up to 256 GB. They are preferred over the other conventional storage devices like floppy disks or CD ROMs as they are faster, smaller and have a longer life span.  The internal circuitry of the pen drive draws power from the computer for its operation. They have an integrated USB interface to communicate with the computer. The important parts of the pen drive are USB connector, crystal oscillator, memory chips and a controller to interact with the PC. The pen drive used here has storage capacity of 4GB.