Product review (5 stars): Upgraded design replacement for plugging or missing rubber condensate grommet/valve.
I had an evaporator freezing and condensate overflow/leaking problem because of an open defrost thermostat, and when I defrosted and checked for correct condensate drainage, I found no rubber grommet/valve on the condensate drain tube, so I installed this upgrade p trap tube to replace the missing part. This part and the thermostat fixed problem. A dab of silicone grease on the inside and outside of included white tube adapter allows easier installation of adapter and p tube flange. No installation instructions are included, but it is easy to find a youtube video, if needed.  Price varies much - I got it for $8.76, so it wasn't worth trying to get a free one through Whirlpool support, and Amazon is faster!