I just purchased this for my Simple Modern 32oz Ascent which uses the standard opening and it does not fit. I also tried my Hydro Flask and Kleen Kanteen tops (which are interchangeable) and they did not work either. They will not thread in. I bought this because it has the same rounded type threads as the existing cap but that made no difference. The Simple Modern measures out about 1/64 inch narrower which seems to be just enough to prevent it from fitting.