MERV stands for Minimum Efficiency Reporting Values and report a filter's ability to capture larger particles between 0.3 and 10 microns (µm). 

• - This value is helpful in comparing the performance of different filters;

• - The rating is derived from a test method developed by the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) [see www.ashrae.org];

• - The higher the MERV rating the better the filter is at trapping specific types of particles;

• - The GreenTech HEPA + Odogard i.e. has a MERV rating of 9.