Hard to install but good protective seal.
These filters look pretty cool when you install them to the mask. Seems to work okay. I can't really tell if it makes a large difference with or without. Installation is definitely not for everyone. It was tough to lock it together but I rather have it well sealed and hard to remove than easy to install and not protected. The reason why I bought these was to help with the airflow with mask because I'm a heavy breather and always fog my sunglasses. I think it works but no matter what, my sunglasses still fogs up a little. ymmv.
Rating: 4 stars