In my experience those are really fine stoppers but they use dedicated brake pads that are waaaay to expensive (and only a matter of time before Shimano stop supporting them).
They don't they're just standard pads and standard holders. The bolts and spacers are unique though.
@tallsam started
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In my experience those are really fine stoppers but they use dedicated brake pads that are waaaay to expensive (and only a matter of time before Shimano stop supporting them).