Our mask cover is designed to fit over an N95 respirator, and will not interfere with the seal of the respirator if worn properly. The N95 should still be worn as usual, with the cover tied over it; the mask cover is NOT intended to improve filtration of the N95. The mask cover is designed to fit over cup-style N95 respirators, but it will fit over a variety of styles.
Unfortunately, extreme shortages have forced facilities to reuse N95 respirators to the point at which they are visibly soiled. The mask cover is intended to protect the N95 from droplets and hopefully extend its usable life in this and other scenarios.