This is for one silicone replacement washer (approx. 2 1/4") that fits an Ortega 2" anti backflow valve. This replaces your worn out or leaking washer. I suggest replacing the current washer by removing the rivet with a drill that holds the current sealing and metal washer and replacing the new washer and metal washer stiffener using a stainless steel or aluminum 1/8" by 1" bolt and washer; then sealing both sides of the bolt with a silicone sealer to prevent the bolt from oxidizing.
The pictures show the original part that I rebuilt and the replacement part available elsewhere. The rebuilt part has been in operation for over a year with no signs of wear. The original washer was not silicon but a "normal" washer that wore out in my one-way valve.
The last photo shows my original, worn out washer next to the silicone washer in this listing.