I think flc8s are designed for deep insertion especially with those long nozzles. Deep insertion has its own benefits over shallow insertion for example lesser but tighter bass and better treble response. The stock tips that is one step bigger then the smallest size is perfect for my ear in terms of seal but not in terms of comfort. Spinfits cp100 s which is 11mm is smaller but gives perfect comfort. Spinfits remove some glare in the lower treble region that stock tips has and thus provide better details and pinpoint accuracy. If jvc can beat them in this point then imo it's the best eartips for flc8s. Perhaps i should order the ms size because s with 10mm would be too small.