The original Electro Voice 70534 foam has been discontinued. This is The Speaker Exchange version of the 70534 tweeter foam used in MS802, 889753A, 89478.
2.35″ outside diameter with .75″ cutout. Sold individually. You can use spray-glue or latex to apply.
(This is the inside foam. Additional photo shows this foam used with outer foam 70604-1)