Product review (3 stars): Works-but it will break
You have to have a knob and these fit and work for up to a year before breaking and having to be replaced.  Have had the stove top for 8 years, and it still works great.  Have replaced every knob once or twice in eight years.  Super glueing crack in plastic base will extend life by a month or so.  Would be willing to pay much more for a metal fixture that never had to be replaced.