Machine made plastic gasket for an 1801 Auto Lite Mirror.  This is for the dual post mirror used on many late 50's through very early 60's MoPar cars.  The listing is for the plastic gasket only. The mirror is not included.  This is made of UV stabilized plastic, so it should hold up well.  You can see small machining marks on the outside edge of the gasket.  Still a nice replacement part that should work well and last a long time.