The filters are quite stiff, you have to fold or roll up to get through the Velcroed gap. Not sure if this affects the effectiveness off the product.
Mask is small/short, ie from nose to mouth, only just covers nose & bottom lip; if you wear glasses, pulling to top of the nose to prevent steaming up, then very close to not covering mouth.
I use this mask over a surgical mask, which helps to keep it in place.
Not really fit for purpose if you're expecting to be able to talk, move around etc....