Minimum Efficiency Reporting Value, or MERV for short, is a filter rating system devised by the American Society of Heating, Refrigeration and Air conditioning Engineers (ASHRAE) to standardize and simplify filter efficiency ratings for the public. The higher the MERV rating, the higher the efficiency of the air filter. Simply stated, a MERV 12 filter will remove smaller particles from the air than a MERV 8 filter. For the consumer this means that you now have the ability to effectively compare one filter to another. In general, any MERV 8 or 11 filter will perform about the same as any other MERV 8 or 11 filter, respectively. The MERV rating only applies to efficiency. Additions such as carbon, Lysol anti-bacterial treatment and Arm & Hammer baking soda are value-added benefits and are not an expression of the MERV rating system. If allergies or asthma are your concern, we suggest you choose a MERV 8 filter or higher.