I used them with a set of Shure SE315 earbuds. I mentioned the Apple ones because that's what many people have today and are similar in price. The fit on mine

I used them with a set of Shure SE315 earbuds. I mentioned the Apple ones because that's what many people have today and are similar in price. The fit on mine from custom insert to the Shures was pretty tight (good for air sealing). I could have drilled the holes a little larger, but it was easier to just warm them up with a hairdryer.