1Applicable Model: Replacement for Vmax 1200 VMX1200 1985?2007; Replacement for Royale XVZ1200D 1983?1985; Replacement for XVZ1200 1983?1984. 2Function: The vacuum diaphragm will automatically adjust the oil intake and the oil air mixing ratio with the change of engine speed and pressure. 3Better Engine Performance: The vacuum diaphragm ensures continuous oil during rapid acceleration, no flameout when idling, and easy cold start. 4Durable Material: Carburetor diaphragm is made of rubber and metal material, meet or exceed OEM manufacturing standards, durable and practical. 5Perfect Fit: Easy to install and use, direct replacement for old carburetor plunger diaphragms, perfect match to the stock carburetor.