Sony 4 GB High Speed Memory Stick PRO Media (MSX-4GN) (Retail Package) 4 Gigabytes storage capacity with approximately 3.66 Gigabytes available Support read and write speeds up to 80 Mbps when used with high speed enabled devices Support read and write speeds up to 80 Mbps when used with high speed enabled Backwards compatible with most Memory Stick PRO media enabled devices Like all Memory Stick media, it is amazingly compact and easy to store