Nuclear Grade VariCels are a series of medium and high efficiency rigid cell side disposable air filters for removal of atmospheric dust and particulates from nuclear power plant air streams. These filters have low initial resistance, high dust holding capacity, and a choice of three efficiency ranges. These filters are designed for use as prefilters to extend the life of AAF AstroCel HEPA filters or as separate duct or line mounted units where HEPA efficiency is not required. more info