Clear Plastic Washer Seating Ring Reducer. Used to reduce 7/8" or 1" bobeche center hole to 3/8" (1/8 IP slip). Raised inner edge holds bobeche in place.
 
Size: 1-1/4" outside diameter, 3/8" inside diameter (1/8 IPS), 7/8" diam raised seat, 1/8" thick