In 2006 Sony and Sandisk introduced the third form factor memory card in the Memory Stick family, after Memory Stick PRO and Memory Stick PRO Duo. The new much smaller Memory Stick Micro is about one-fourth the size of Memory Stick Duo. Memory Stick Micro or M2 is aimed at use in mobile phones and ultra small portable devices.
The Memory Stick Micro is based on the PRO platform, which is used by both Memory Stick PRO and Memory Stick PRO Duo cards, meaning that it can offer high storage capacity and high transfer speed in a much smaller physical format. The only difference from the PRO cards will be the fact of having lower operating voltage through being dual-voltage. This will meet the demand from the electronics manufactures for lower power consumption contributing to longer lasting battery life for mobile phones and other portable electronic devices.
Micro Memory Sticks (also known as M2 sticks or simply M2) come in a variety of pack configurations, either with an adapter so it can be used as a ProDuo stick or with a dedicated USB reader so you can access its contents easily on a computer. Some packs come with both, or just the M2 stick on its own if you already have an adapter/USB reader.