Adapter connects the 21.5mm x 1.5 female threads of your Moen faucet to 55/64" female threads of the diverter valve.
These Moen faucets may use the unique 21.5mm x 1.5mm threads:
Danika 64753
Danika L84753
Ashville 84778MBRB
Ashville 84778MSRN
Method 6810, 6810N, 68100
Eva 6400
Brantford 6600
Hensley
Kleo WS84900