Of all the filters, 
Why  should  be NANO-BEVONDTE? 
Most existing masks are less efficient  due to moisture generated when breathing in an electrostatic  manner. 
NANO-BEYONDTEX is 0.1 µm larger than air particles and smaller than harmful particles, and is filtered  by the nanofiber  structure  itself, allowing for long wear and breathability,  blocking, and durability.