OEM Aprilia Diaphragm -#2R000307 (ex AP0260891, AP0260890) For'98-'03 Mille, Mille-R, '00-'03 Falco, '01-'03 Futura, '01-'07 CapoNord, '02-'05 Tuono, '04-'09 RSVR, RSVR Factory, and '06-'10 Tuono, Tuono Factory.
OEM Aprilia Diaphragm -#2R000307 (ex AP0260891, AP0260890)
For '98-'03 Mille, Mille-R, '00-'03 Falco, '01-'03 Futura, '01-'07 CapoNord, '02-'05 Tuono, '04-'09 RSVR, RSVR Factory, and '06-'10 Tuono, Tuono Factory.
Part no 14 in the diagram at the link below
https://www.af1racing.com/store/Scripts/prodList.asp?idCategory=207