I am having a real hard time getting the seal I need, with the biggest tips. My brother solved that by using the CX300II largest tip. I struggle badly to get it right...then they unseal so easily. He wont give me them tips as he retains the CX300 because the Piston has some kinda issue with the a button and muting for his purposes. The thing works perfectly on my Google phone.
Complys or Shure Olives might work for most ears, judging from their shapes. I, too, get a fiddly fit with their tips, and I learned it's mostly the tips' fault as they are a lot stouter than I'd like. I haven't tried Shure Olives with them, but I have with Complys, and they fit me particularly well. Complys do wear out fast, though.