Seems to be a high-quality bite, seems to be sealed on both sides. I cannot confirm the number of particles. I don't have a counter for PM 2.5 and 0.3. (Maybe I can get one) The adapter has a nice o-ring that looks like it would fit the v7 case, the adapter ring square gasket filters nice and high and I can feel the squeezing crimp filter. It should be better than the crappy Dyson foam that came with removing the v7Adapter, a little tugging and tugging, hope something doesn't break, mine…