What is "Beta Ratio"

[RWEST]

So, I'm looking at the Wix chart, trying to cross a John Deere filter, and I see the 51064 has a 2/20=14/30 Beta Ratio, while the 51334, the longer version, has a 2/20=22/40 Beta Ratio. What does that mean?
Does one filter more than the other?
Smaller particles?

 

[J_Rod]

The way I understand it is the 51064 is 50% efficient at stopping 14 micron and 95% at stopping 30 micron. The first part of the equation is the percentage and the second is the micron size. To get the percentage subtract 1 from the number given, i.e. 20-1=19, then divide 19 by 20=95%, this shows the percentage for 30 microns.

 

[ZZman]

http://www.gopani.com/appendix4.htm