Trans-flash Card or Micro SD Card. 

Micro SD Card, formerly known as Trans-flash Card (TF card), was officially renamed Micro SD Card in 2004. It was invented by SanDisk and is mainly used for mobile phones.

Before the launch of Micro SD, mobile phone manufacturers used embedded memory. Although this type of module is easy to install, it has the problem that it can not meet the actual demand of the trend - the capacity is limited and there is no room for upgrading. Micro SD emulates the application mode of SIM card, that is, the same card can be used in different models of mobile phones, so that mobile phone manufacturers no longer have to worry about plug-in R&D and design. Micro SD card can be regarded as a removable storage IC.

Micro SD card is a very small flash memory card. Its format is created by SanDisk. This memory card was originally called T-Flash, and later called Trans Flash; The reason why it was renamed Micro SD was that it was adopted by the SD Association (SDA). Other memory cards adopted by SDA include Mini SD and SD cards. It is mainly used in mobile phones, but because of its small size and continuous improvement of storage capacity, it has been used in GPS devices, portable music players and some flash memory disks. Its volume is 15mm x 11mm x 1mm, almost equal to the size of a fingernail, and it is the smallest memory card at present. It can also be connected to the SD card slot through the SD adapter card. At present, Micro SD cards offer capacities of 128MB, 256MB, 512MB, 1G, 2G, 4G, 8G, 16G, 32G, 64G and 128G (During the MWC 2014 World Mobile Communication Conference, SanDisk (Sandi) broke the tradition of memory cards with a maximum capacity of 64GB and officially released a Micro SD XC memory card with a capacity of up to 128GB.