I currently am using the open bass 8mm Philips domes with my 9030 HA from Costco. The right one is a good fit but the left one is a bit snug. Both are sort of snug when pushing them in place. I think there is a narrow area in my left ear canal that must be overcome to get this dome in place and once I pass that, which I can feel, then it’s not bad. Lots of initial itch in spite of using that comfort oil every night. But the Philips domes are not very flexible and the 6mm size is just way too small and occludes the receiver. The 8mm domes I had on my Rexton BiCores did not have this issue and are more open and therefore also more flexible and easy to put into my ear. And I see that Phonax has a 7mm open dome size that might be perfect for me. Are these domes interchangeable as long as a I stay with the same open style? Are they all click domes? I don’t want to lose one in my ear, lol. Thanks