My molds are ~hard silicone molds made by ReSound with “Select-A-Vent.” They stay in place very well, perhaps because of the shape of ear canals (matching undulations in molds) but each mold seems to have a slight upper lip or protrustion perhaps designed to catch on my crus helicis arch on the upper outside of each ear canal. Widex Evoke Custom Mold popping out - #2 by jim_lewis and Widex Evoke Custom Mold popping out - #6 by jim_lewis.