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