I beleive it was 2 microns but don't quote me yet.
Blue gloves for milk that used for "blue cheese" Brown gloves for chocolate milk and white gloves for white milk

city boy
5 bottles at once, user friendly.
The gloves fit really tight around the cartridge and seals well.
The setup is for emergency use if necessary. Boil your water if all fails.
Udder than that, the project was fun and moooving in the right direction at the time.
Edited:
A quick search gave us this:
http://www.wisegeek.com/what-is-a-hepa-filter.htm
The rating for a HEPA filter is based on capturing nearly all microns .3 in size, verses .1 or even .001 because .3 microns are the hardest size to trap and the optimal size for passing into the human respiratory system. Therefore the .3 micron efficiency rating sets the highest standard.
A HEPA filter is so efficient that for every 10,000 particles that enter the filter within its filtering range, only 3 particles will get through. Surprisingly, HEPA filters become even more efficient the longer they are in use.
For this reason HEPA filters are used in environments that rely on high clean-air standards. Surgical facilities, tuberculosis wards, NASA clean rooms, and laboratories are a few examples of environments that utilize HEPA filters. HEPA filters are particularly useful for allergy sufferers.
Many imitations of HEPA filters pervade the marketplace, usually called HEPA -type filters. They are less expensive than true HEPA filters, rated lower, and do an inferior job of filtering the air. If your health requires the specific benefits and efficiency of a HEPA filter, check the packaging to make sure the filter is rated at an efficiency of 99.97% for microns .3 in size. If it's a true HEPA filter, it will have this rating clearly marked. <a href="
http://www.wisegeek.com/what-is-a-hepa- ... il">Source - What Is A Hepa Filter?</a>