I thought I'd write a quick review of using the BBQ Guru Pit Viper fan and their Blaze Kamado adapter.
The adapter comes as two pieces, one for inside the grill and one for outside.
There are two hex-head screws and wingnuts to cinch it down in the opening.
It seems it's designed to go in from the inside, but I wanted to try to slip it in from the outside.
Here's my first attempt at that
This didn't work because the second bolt couldn't be pulled through the outer plate and cinched down.
Next I added jam nuts and washers (from my shop "spare parts bin," these are not included):
With those, I was able to insert the back plate and pull it through-- it was a tight fit with the bolts pressing against the Blaze's vent opening:
but it worked:
However, the front plate is not quite large enough and just barely covers the opening:
It did perform well with the fireboard and its motor control cable.
Note that although the cable has a separate input for the motor power, the fireboard itself will drive it without that.
I used an aux USB battery to keep the fireboard energized:
Hope this helps. Would I buy it again? Yes, but I wish BBQ Guru included the jam nuts and washers. I also was surprised that the front plate just barely fit the opening. It should be larger by about 5mm.