This microSD card crams 400GB of storage into your smartphoneWestern Digital just showed off “the world's highest-capacity” microSD card. The SanDisk Ultra microSDXC UHS-I crams 400GB of storage into your smartphone. It’s the highest-capacity microSD card for use in mobile devices. It can hold 40 hours of Full HD video and can transfer data at up to 100MBps. At that speed, you can move 1,200 3.5MB photos per minute over USB 3.0. The card is being aimed at Android smartphone and tablet users. It comes with a 10-year warranty and a US retail price of $249.99. Western Digital says its production processes allowed for more bits per die. Only two years ago, Western Digital's biggest microSD card stood at 200GB for $399. When the microSD card format first launched in 2004, it had 128MB of capacity.