How on Earth are SanDisk 400GB microSD cards down to just $57?

Amazon has been running a fantastic sale on SanDisk microSD cards that matches all-time low prices on the two most popular sizes -- 128GB for $19.99 and just $11.50 for a 64GB card. If you want more space than that though, today is your lucky day because SanDisk Ultra 400GB microSDXC UHS-I Cards are back in stock for just $56.99 each!Here's some more info from Amazon's product description:* Up to 400GB (1GB=1,000,000,000 bytes. Actual user storage less.) to store even more hours of Full HD video