Introducing the Inner and Outer Air Filtration Replacement Filter by POWERTEC. OUTER FILTER: 5 Micron Filtration Grade Airborne particles are extracted and trapped in your filtration system and not released into the air that you breath. Not only are these filters capable of intercepting particles that are 5 microns or larger – but they'll help eliminate those unwanted particles that can contaminate the air and your workshop surroundings. Additionally, the outer filter helps prolong the lifespan of your secondary filter. Thus allowing your dust-collection system to operate at an optimal level with maximum effectiveness. INNER FILTER: 1 Micron Filtration Grade Providing a high efficiency than fiberglass filters, this version is able to remove particles down to 1 micron in size. Airborne particles are extracted and trapped in your filtration system and not released into the air that you breath. Compatible With: WEN 3410 Grizzly G0738 Shop Fox w1830 & others! These Air Filtration Systems are commonly used for: Woodworking Food & Beverage Medical Biotechnology Cosmetic Chemical Processing POWERTEC is a leading manufacturer of high quality woodworking tools and accessories, machines, and an assortment of OEM replacement parts. We are committed to exceeding expectations, while bringing the latest innovations, technology, and product development to the industry