Factory spec MAX Rated at 250 BAR however I personally only fill to 200 BAR (2900psi) so the regulator is more reliably consistent for accuracy and long reliability.
All brands not only FX to keep the regulators working reliably for consistency and longevity sake. Often fill pressures past 3000psi makes regulators not provide bulletproof consistency and reliability.
Only the long distance accuracy shooters know this secret with the lower fill pressure trick.