The N95 mask is one of 9 types of particulate protection masks certified by NIOSH. "N" means not resistant to oil. "95" means that when exposed to a specified number of special test particles, the particle concentration in the mask is more than 95% lower than the particle concentration outside the mask. The 95% value is not the average value, but the minimum value. N95 is not a specific product name, as long as it meets the N95 standard, and products that pass the NIOSH review can be called "N95 masks."