And Russian oxygen generators.
As I understand it no one else makes a model anywhere near as reliable or robust. The Russians do have some damn good long term orbital experience, it has to be admitted...
Last I heard of the NASA ones (A few years back, admittedly) their costs were ballooning and their multiple capacities outdid the RUssians...but did not work on a relaiable basis. Too many bells and whistles added on without proper planning. I suspect Managemnt pointyheads had more of an input on what was to go into the design than the engineers ever did.