Castex vacuum bags use superior Micro-Plus filter media with a melt-blown inner liner that allows it to achieve filtration up to 99.9%. Their micro-filtration bags with dust seal closure are ideal for allergy filtration. The Micron Filter 2-Ply Janitized Plus vacuum bags with Dust Seal have a 99% micro-filtration rating and are 46% stronger than OEM 2-Ply filter bags and provide a 40% increase in airflow. Better filtration results in cleaner air, secondary filters lasting longer, and spending less time dusting.