Product review (5 stars): Worked perfectly
6 years ago my whirlpool microwave push button latch stopped working- I pushed the button and nothing.  I had the repair people come out and $184 later they put this little plastic piece in.  This is the exact piece I paid 5x the price for (plus labor).  Flash forward to the other night when the same thing happened-- this time I knew what to do.  All you need to install is a 'tamper proof star key set' (to get inside the microwave), and a Phillips head screwdriver.  It took less then 5 minutes to put in and put the microwave back into the wall.  This is such an easy repair anyone can do it and save $$$.
The Microwave model I have is the Whirlpool MT4155SPQ manufactured 2004.  But it works for multiple models (just google).