I’ve solved the same problem with my OPN1’s. Kept slipping out. I haven’t had these very long and was driving me mad. My audiologist gave me size 8 double vent. He will probably kill me, but this is what I’ve done: I now have size 10 open domes. Of course these are too big for me! Each dome has 6 holes joined by a band at the bottom edge. I simply cut completely through the band beneath each hole (6 cuts). Since I did this they never move, are comfortable all day and the hearing is so much better and natural with more outside sound coming in. This may not suit everyone as all our hearing problems are different. But it works great for me. Hope this helps.
You’re ignoring this member’s posts.