In a post on Twitter, MangoPi announced its new SD card-sized device that’s smaller than the smallest Raspberry Pi. The device which is still unnamed features a Linux-capable SoC, and has no ports. Hence, an external carrier board will be required for programming and interfacing. This carrier board can be seen in the images released by MangoPi. The Twitter post also specifies that the board can run 1080p video at 60Hz over HDMI.
The device with the carrier board (Credit: MangoPi)
According to the photos MangoPi released, here are some features of the device:

Processing units: Allwinner H616, Vulkan 1.1-capable GPU
Four Arm Cortex-A53 cores
Can run Tina Linux
Maximum Memory: 4GB (DDR3 and 4)
8-bit NAND Flash interface with ECC
SD 3.0 interface
Supports full disk encryption with AES, XTS
160-bit hardware pseudo-random number generator
Integrated EFUSE chip for ID and security
Tamper-proofing using MD5 and other methods
Its video engine can decode H.264, H.265, VP9
HDR with 10-bit processing
Two digital audio channels
The carrier board includes the following:

Gigabit Ethernet
USB 2/OTG
Another 100MBs Ethernet interface
UART
PWM controller
SDIO
A power delivery system

The most notable advantage that this board will provide is the capability to make more advanced IoT devices thanks to its form factor. This device will heavily benefit the wearable electronics industry, since wearables require the size and weight of the system to be as small as possible. Moreover, having Linux capability in a device as small as an SD card is remarkable.
The board isn’t available for sale, since it is still being experimented on. MangoPi hinted in its Twitter post that it will be testing out the Armbian operating system next. It’s possible that the board will be called the ‘Linux Box,’ as the Mango Pi website has a blank product page with that name and there’s talk about it on their forum.