Product review (5 stars): Perfect fit.  Super easy.
This part came quickly in the mail and fit our microwave exactly.  It replaced the 7 year old ring which had lost a wheel.  I actually kept the old ring in a drawer just below the microwave--just in case another wheel breaks.  The wheels can be popped on and off easily.  You can easily place the  new ring in the center hole.  I did a short 5 second test run without the glass plate and it worked perfectly.

I found our microwave model number on the inside of the microwave on the left side, not on the door.