This them i take it
https://www.smaxtec.com/en/
Work used a number of that type of bolus a few yr`s back .(Doubt it was this make ) Well the feed supplier put a similar type bolus in i think 5 (maybe more) cows to track there rumen activity . Biggest issue with them was the inability to get the info that the bolus was taking out of the cow . The data transfer from the bolus to the scanner that was been used was very hit and miss it missed more than it hit and they eventually gave up trying to get the data . They`v probably improved the system now that it`s been sold to the farmer directly but still early days i say for this type of system .