If you also found the Pixel site is a little unclear on how to upgrade the Pixel King Pro and King. This is your one stop page for upgrading Pixel King and King Pro TTL flash remote trigger.
The file content the following firmwares. Download here
King Pro Nikon v1010
King Pro Canon v1010
King Canon v1041 1Dx
King Nikon v1021
King Sony v1020
Instruction is enclosed with the file. Password to extract the file is “swsm”