Product review (4 stars): Not for "installation" wtih Whirlaway, but works adequately inserted from the top.
I ordered this for my Whirlaway 584 disposal, for which the OEM splashguard is no longer separately available. This is *not* the same piece. In other words, it's not a direct replacement for the OEM part. The OEM part requires removing the disposal from the bottom and replacing the guard from underneath the sink. This part does not work that way and will not fit that disposal.

However, it *does* fit into the opening from the top. It appears this is the intent of this unit, and for that purpose, it does work. However, the very top lip (visible in the picture) is plenty small. When inserting it into the opening, it is possible (even somewhat easy) to shove it right down into the disposal. Don't worry, it's just as easy to get back out.

When properly inserted, it works as it should. So far, we have not encountered a problem with the splashguard coming unseated and going down into the disposal. All of the users have been instructed not to shove large items down the disposal with significant force and that appears to result in sustained correct function.

My only complaints are: 1) that it's not clear from the marketing material that this is not a direct replacement for the OEM part, and 2) that it's a bit easier than I'd like to shove all the way down into the disposal. Both problems are addressed as described above. The positive of this part is that it does not require removal of the disposal. Just push it down in the drain and go.