I needed to mount my ANGi sensor to a 3rd party helmet and it seemed I ought to mount it to the harness rather than the exterior of the helmet given a) that's where it mounts on the Specialized helmets and b) my helmet has a MIPS harness, so the helmet outer shell's movement can be very different from my head's. Sadly, the recessed area in the rear band of my helmet harness is too narrow for the ANGi sensor.
I ordered this adapter to fill that recessed area and provide a mount point for the sensor. The adapter is the right thickness for my purpose but is also too wide for the space. It was, however, fairly easy to cut down to size. It now fits within the recessed area of my helmet's harness band and provides a good surface for mounting the sensor. The adhesive seems secure (only two rides so far).
So, the adapter serves the purpose and is "universal" if you have heavy clippers or a fine-toothed saw. But, the price, $17 incl $10 shipping, is pretty nuts for a few grams of plastic.