Nuova Simonelli have switched back and forth from this flat style to the conical version numerous times. Either will work and there is no discernible difference in performance, it is a simple matter of personal preference. This version fits commercial models such as the Appia and Appia II (except the Aurelia, Aurelia II, and Aurelia Wave, which use S_418), as well as the Oscar model.
For the home units, such as the Ellimatic or "Elli" use S_1.
WARNING: This product can expose you to chemicals including lead, which are known to the State of California to cause cancer, birth defects, or other reproductive harm. For more information, go to www.p65warnings.ca.gov.