Cougar 700K Gaming Keyboard Support Coming To Linux 4.21
Earlier this year there was the introduction of the new Cougar HID driver initially for the 500K driver. That driver was needed to support various special function keys on the keyboard with those keys using a custom vendor interface while the standard functionality of the keyboard is fine and respects HID standards in that regard. With the Linux 4.21 kernel, the Cougar driver is being extended to the 700K series.
It's just the new USB device ID addition that's needed, which is now queued in hid-next ahead of the Linux 4.21 cycle. That will allow the 700K keyboard to be working properly with the mainline Linux kernel. Fortunately it's a trivial patch should you want to apply it against a Linux 4.19+ kernel with HID_COUGAR right now.
The Cougar 700K is a mechanical gaming keyboard with aluminum frame structure, Cherry MX mechanical switches, a variety of extra keys, LED backlit, and other gaming-focused features. The 700K retails for $80~100 USD.