Hi @bodenis, thanks for reaching out. The accuracy of our eye trackers is not a single metric per se but varies according to use case and environmental conditions.
We have produced an extensive guide to the concepts behind ET accuracy which you can read @
In terms of final metrics, we have not produced a whitepaper for this model (as the intention is for gaming, not research) however a paper dealing with the older generation EyeX contained derived values which are comparable to the 4C.
You can view this paper and the values @ https://www.researchgate.net/publication/305213481_Evaluation_of_the_Tobii_EyeX_Eye_tracking_controller_and_Matlab_toolkit_for_research
Hopefully, this should provide you with the results you are looking for! Best Wishes.