Even though the building blocks of the mechanically stable USMOF DB MOFs were obtained from CoRE MOF 2019, there are significant differences in properties of the two MOF databases. These differences are evident for both gas molecules but especially apparent for CO2, both in the distribution of gas working capacity values and in feature importances of the ML models trained on the two sets (see Figure ). To elucidate the reason for these discrepancies, we next analyzed the MOFs in USMOF DB that exhibit exceptionally high CH4 working capacity.