If coarse dust is a problem, the IQAir PF40™ Kit can be added to almost any IQAir system. It allows the air purifier's standard pre-filter to be more effective by trapping additional coarse dust in environments with elevated levels of larger particles. This makes the PF40™ Kit a perfect solution for desert locations and other environments with high levels of dust, and also commercial applications such as bakeries or spaces affected by feather dust from birds, etc. Total filter life remains the same for all filters even with the addition of the PF40™ Kit.