Possibly never installed NOS but selling as used because I don't know for sure. It looks like it could have been used for a mockup because it has a little tape and glue residue. (see pics)
Has some mild shelf wear but no major defects.
13" outside diameter and fits an 12" hole. Backing mount plate is included.
Please look closely at the photos as they are the best description of this part. Feel free to ask questions or ask for more photos.