Hey Guys, I gotta share this with ya, I have been rehabbing homes in Minneapolis for 23+ years, love my job but hate the dust. A buddy of mine that rides ATVs showed me a mask that he had bought. I have a crew of eight guys we used to go through a of 3M 8511s a day, and it was costing me about 85 bucks a week. I decided to pick up a dozen of the replaceable filters for each guy. Each filter can be washed and reused several times. Now each guy goes through about one replaceable filter per week, saving me around 70 bucks a week. I highly reccomend checking them out for yourself.