Green serial G6 (three colors) have advantage feature:
Negative-ion:
Release Ions, which can absorb suspended particles and make it precipitated from air. Ions are also healthful to human being. G6 can release 5millions ions/CM3.

HEPA Filter:
HEPA is made according to PM0.3 standard. That means it can remove 99.7% 0.3micro metro particle from the air.
Active carbon:
Active carbon can absorb the odor and chemical gas like TOC, VOC from the air.