This ST1100 replacement diaphragm is guaranteed to fit.

If you cannot install the diaphragm yourself (some years are easier than others), you can send the slide or slides to us (slide needles removed) and we will install it for free and ship it back to you for only the cost of shipping.

It is always recommended to replace all of the diaphragms together (4 are required for the ST1100). This listing is for the sale of only one diaphragm.