They offer both 8mm and 11mm stem sizes for internal sensors; you probably got the 8mm...
https://sykik.com/collections/wireless-tire-pressure-monitor/products/inner-tire-pressure-monitor
I was wrong about saying I ordered the actual SRTP400 kit and didn't realize that until I looked at your link.
The kit that I ordered had 90 degree valve stems and there was no information about the stem diameter.
This kit was listed as SRTP400 when I purchased it.
But I now think it was a kit some reseller made up using these 90 degree valve stem sensors, which are compatible with the SRTP400 receiver but are available only with 8mm stems.
https://sykik.com/collections/wirel...ucts/internal-sensor-for-cars-and-motorcycles
It was the 90 degree valve stems that would not work with the FJR wheels.
Thanks for making me look again, dammit !!
dan