... filter 1)Prolonged service; 2)Nontoxic, odorless; 3)Refined filter structure; 4)Super air flow; Multi-colour Dust Filter ... intensive layer and embodies the integral advantages of multi-stratification and ascending filtration requirements, guides the wind ... Nontoxic, odorless, disposable, reasonable filter structure stretching the service life of product,Small resistance, high efficiency, uniform ...