Certified HEPA Filter and Fabric Pre-Filter for RIDGID HEPA Vacuum RV2400HFNew EPA regulation now in effect requires the use of a certified HEPA filtration vac, along with other specific cleaning techniques. This certified HEPA Filter is 99. 97% efficient at filtering particulates down to 0. 3 mic in size when used in conjunction with the RIDGID RV2400HF wet dry vac. The filter is water resistant and durable for easy cleaning and re use. When used in conjunction with the RIDGID vac, RV2400HF, the vacuum system is HEPA