As I recall there was only one diaphragm used in the 120. Just the diaphragm and a gasket. Look it up on Centrals web site. Buy 3 of them. I buy them just as a filler when ordering from Central to offset the shipping on the small orders I make. I need to place an order myself but waiting until fall when I start flying a lot more. I hate getting up early to beat the heat and wind!!!