Raspberry Pi is not only a single board mini computer now. It now becomes a portable plug and Plays computer embedded in Keyboard itself. This 28 cm keyboard equipped with the latest generation Pi board Featuring a quad-core 64-bit processor, wireless networking, dual-display output, and 4K video playback, Raspberry Pi 400 is a complete personal computer, built into a compact keyboard with Raspberry Pi Red-White colored signature design.
It will work with all your old Raspberry Accessories like Power supply, HDMI cable, or Mouse, etc.
Raspberry Pi 400s appealing design will add a cool style to your Raspberry pi eco-system. It has easy access to all ports including LAN, GPIO, and SD card at the top of the Keyboard.

Key Features:

Faster processing:

With one of the latest Broadcom 2711; Quad-Core Cortex A72 (ARM V8-A)  64-bit SoC Clocked at  1.8GHz  processor.
Video performance on Raspberry Pi 400 is upgraded with dual-display support at resolutions up to 4K via a pair of micro-HDMI ports; hardware video decode at up to 4Kp60 which supports H 265 Decode (4Kp60); H.264, decode (1080p60).

Faster wireless:

A significant change on the Raspberry Pi 400  is the inclusion of a new faster; dual-band wireless chip with 802.11 b/g/n/ac wireless LAN.
The dual-band 2.4GHz and 5GHz wireless LAN enable faster networking with less interference and the new PCB antenna technology allows better reception.
The latest 5.0 Bluetooth allows you to use Bluetooth devices with more range than before without extra dongles; keeping things nice and tidy.

Enhanced Ethernet Connectivity:

The Raspberry Pi 400 has significantly faster-wired networking with USB 3.0 technology; thanks to an upgraded USB/LAN chip; and you should see speeds that are 10x faster than on previous models of the Pi.
The GPIO header remains the same, with 40 pins; fully backward-compatible with previous boards as on the previous three models of Pi. However; it should note that the new PoE header pins may contact components on the underside of some HATs; like Rainbow HAT. Some standoffs will prevent any mischief from occurring though!