Filters have different uses, and therefore there is a need for different filtration efficiencies for removing various particles.
"Beta Ratio" is used to define the filtration efficiency, shortened with symbol β.
Beta ratio defines how effective the filter is. For example: at 10 microns, Beta 20 releases 1 in 20 particles that are 10 microns through. At beta 1000, 1 in 1000
Beta values can be listed as β(my): 2, 10, 20, 75, 100, 200, 1000, and 2000