The 1n's and 2n's ARE affected by the prism foam. I received my tool set from Beljan today and (in between rediculous political sniping in the soap box) performed the operation on my beater OM-2n. It went remarkably well, and I'll be doing the rest of my OM bodies soon. I can't say enough good about Joe Beljan's OM tool set, it's probably the best $40 I've spent on ebay in quite awhile. (usual disclaimer: I have no financial interests with Beljan Mfg.)