At present, a plethora of MP4 players with unique features are available in the market. One can choose on the basis of his/her needs and budget. These gadgets are available in various storage format like Flash memory cards, flash internal memory and hard drive storage. Moreover, the memory allocation can be hybrid, which means flash memory based MP4 players can have expandable memory feature via flash memory cards. This means a 4 GB hard drive digital AV player can have expandable memory up to 8 GB by addition of 4 GB of Flash memory. Many large and small companies are manufacturing these digital AV (Audio-Video) players and with it there are many models of MP4 players available in the market.