It says support for 4K, but it does not appear to record 4K.

HDMI Specific Features

Support for up to 4096x2160 4:4:4/4:2:2 30fps or 4096x2160 4:2:0 60fps input and loopthrough signals
Support for 8/10/12-bit color depths
Support for 60p, 60i, 50p, 50i, 30p, 25p signal formats

Analog Audio Features

Extraction of stereo embedded HDMI audio for recording and output via 3.5mm stereo mini-jack Line Out
Recording and streaming analog audio via 3.5 mm microphone interface

Streaming Features

Support for live streaming using RTMP protocol to software including Flash Media Server, Wowza, Red5 and Nginx server
Streaming to Facebook, Twitch and YouTube platforms
Support for streaming to 2 servers simultaneously

Recording Features (to USB Flash Drive)

Support for H.264 High Profile (video) and AAC High Quality (audio) encoding
Supports recording at input signal resolution up to 2048x1080
Support for 1920x1080, 1600x1200, 1440x1080, 1440x900, 1280x1024, 1280x960, 1280x800, 1280x720, 1200x900, 1024x768, 960x540, 800x600, 768x576, 720x576, 720x480, 640x480, 640x360, 480x360 resolutions
Support for 60fps, 50fps, 30fps, 25fps, 24fps, 15fps frame rates
Support for recording as MP4 files
USB Flash Drive file system format: FAT32, NTFS, exFAT, VFAT

My understanding is that it will accept up to 4K 60 (4:2:0) input signals over HDMI, but will downscale to 1080p60 for recording.

What is unclear from the specifications is what bitrate it records at. Only the resolutions seem to be listed and not what record bitrate is used at each resolution and frame rate.