It is a sliding closet mirror door with the piece being a top mount. The only tag on the product itself is shown in the attached pictures above. The part needed is the broken plastic piece shown which holds the mirror door from the top and keeps it in place.
Casey from SWISCO responded:
November 11, 2020
Hello,
Take a look at our 23-044 top guide and see if the dimensions could work as a replacement for the part in your photos. Thank you!