* Less than mediocre performance at filtering 0.3-1µm particles, which are more likely to lead to chronic lung-related conditions.

* OK performance at filtering 1-3µm particles, which are more likely to cause various respiratory problems and other health and productivity issues.

* OK permeability. The lower the permeability score, the more strain the filter would put on your equipment which can dramatically increase the cost of operating your furnace, air conditioner, and heat pump.

* Requires an aftermarket filter housing which could potentially require a professional installation.