I have the 5SAO trigger in both a 75B and 97B-E so would assume the "flat" trigger is compatible with both as well as the part fitted into the frame is the same for both triggers. FWIW, I had the "flat" in the 75B, then had CGW build me a 97B-E using the 5SAO and, after using the 97, I sent the 75B back to them to have the flat trigger removed and the 5 SAO installed in its place. To me, the slight curve on the 5SAO works much better than the "flat" version.