Over the years I have learned the term "false advertisement" isn't something the Chinese understand, or even care about. If his are breaking I am betting they just tossed that stainless description on there to make their product look cool. Or they found a way to make a gummy, soft metal brittle...
I am assuming since his are breaking the GPM ones are a low grade carbon steel. Chinese steel is just the worst. If you break it and look at the cross section you will see it looks like pot metal. Very porous and fragile. Go with factory replacements, or measure the pins and look online for...